{"id":"cb_question_bank:4237133f-815d-412b-9d78-b85126aff976","source_id":"cb_question_bank","source_item_id":"4237133f-815d-412b-9d78-b85126aff976","external_id":null,"ibn":"07822-DC","question_id":"4c95c7d4","program":"SAT","module":"math","domain_code":"S","domain":"Geometry and Trigonometry","skill_code":"S.C.","skill":"Right triangles and trigonometry","difficulty":"H","score_band":7,"answer_type":"mcq","answer_source":"key","layout_warning":null,"form_id":null,"module_number":null,"position":null,"stem":"A graphic designer is creating a logo for a company. The logo is shown in the figure above. The logo is in the shape of a trapezoid and consists of three congruent equilateral triangles. If the perimeter of the logo is 20 centimeters, what is the combined area of the shaded regions, in square centimeters, of the logo?","stimulus":"The figure presents a trapezoid, which consists of three congruent equilateral triangles. Two of the triangles are shaded, and each of those triangles shares a side with the unshaded triangle.","stimulus_html":"<div class=\"stimulus_reference \">\n        <div class=\"standalone_image \">\n          <img src=\"/api/assets/18402612eec0a5a7e9e7e0f7fd50c66214ddf63bfe62ca77a9d080d1149577e8\" alt=\"The figure presents a trapezoid, which consists of three congruent equilateral triangles. Two of the triangles are shaded, and each of those triangles shares a side with the unshaded triangle.\" width=\"124\" height=\"54\"></div>\n      </div>\n","stem_html":"<p class=\"stem_paragraph \">A graphic designer is creating a logo for a company. The logo is shown in the figure above. The logo is&nbsp;in&nbsp;the shape of a trapezoid and consists of three&nbsp;congruent equilateral triangles. If the perimeter of the logo is 20&nbsp;centimeters, what is the combined area of the shaded regions, in square centimeters, of the logo?</p>\n","rationale_html":"<p>Choice C is correct. It’s given that the logo is in the shape of a trapezoid that consists of three congruent equilateral triangles, and that the perimeter of the trapezoid is 20 centimeters (cm). Since the perimeter of the trapezoid is the sum of the lengths of 5 of the sides of the triangles, the length of each side of an equilateral triangle is <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/ca30e502ff2dfc68f7b9016e123c905cea23ab4809a0a0e12e46eb9492adff51\" alt=\"the fraction 20 over 5 equals 4 centimeters\"></span>. Dividing up one equilateral triangle into two right triangles yields a pair of congruent 30°-60°-90° triangles. The shorter leg of each right triangle is half the length of the side of an equilateral triangle, or 2 cm. Using the Pythagorean Theorem, <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/7e77b1686ddd243d00b6eba457256dc24b3e48f0414ac28bb03ee0e080f3222c\" alt=\"a, squared, plus b squared, equals c squared\"></span>, the height of the equilateral triangle can be found. Substituting <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/b8939f0089034fb0b27a6a9b987733739fbdb2c6f74447b4a31584d266b4c797\" alt=\"a, equals 2\"></span> and <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/779adaa3f2712be16a07716ee774e07a78ae20b2a742e9c4e3e9facc41ab8d1b\" alt=\"c equals 4 \"></span> and solving for <span class=\"italic\">b</span> yields <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/c76ecbc657e0956659f16ad157efdf5efba5a9ac48bf34fa169562aad6cd490f\" alt=\"the square root of, 4 squared, minus 2 squared, end root, equals the square root of 12, which equals, 2 times the square root of 3 centimeters\"></span> cm. The area of one equilateral triangle is <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/bf08cb050fa796a8fd903015aa12be25be1c9f2b93327193ca03ff5c969f6986\" alt=\"one half b h\"></span>, where <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/9575f4491dd1ea691fb892d943a6559484f8c037cb47b520371c8479da185906\" alt=\"b equals 2 \"></span> and <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/4c643e63a8d83d7e0741e8d6cee306d8931f342884b3ff21ea9bcadd9a902261\" alt=\"h equals, 2 times the square root of 3\"></span>. Therefore, the area of one equilateral triangle is <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/d40424ceae04bc6eaa67adf55f3e8fd8e828ad0c719353f0317333918ae44e20\" alt=\"one half times 4, times, open parenthesis, 2 times the square root of 3, close parenthesis, equals, 4 times the square root of 3 centimeters squared\"></span>. The shaded area consists of two such triangles, so its area is <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/4a8643f43544670d240c8c6815683e49be3d8039641b0fa8d25572b0320a3fa7\" alt=\"2 times 4, times the square root of 3, equals, 8 times the square root of 3 centimeters squared\"></span>.</p><p>Alternate approach: The area of a trapezoid can be found by evaluating the expression <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/b380629b8d25f83257b14bdb8bf66a247ca6fd98015e36c32ca7b500816895aa\" alt=\"one half times, open parenthesis, b sub 1 plus b sub 2, close parenthesis, times h\"></span>, where <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/8565980c696bc07a80e2630d008f0267ca21227ad912ec7c05b3f6ac31ba6b6e\" alt=\"b sub 1\"></span>is the length of one base, <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/9240404b10bf2e66a3ced39904f8821a9e81a5fea17e0d8d8553d68e974b51c8\" alt=\"b sub 2 \"></span> is the length of the other base, and <span class=\"italic\">h</span> is the height of the trapezoid. Substituting <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/c788004444960320fdbde1db6836c563a9258877ed8b0779acfb03b314970add\" alt=\"b sub 1 equals 8\"></span>, <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/4b8add2b041e52436fc17c2156e62a4bcc5ac5cbbefde1142554a692b1927210\" alt=\"b sub 2 equals 4\"></span>, and <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/4c643e63a8d83d7e0741e8d6cee306d8931f342884b3ff21ea9bcadd9a902261\" alt=\"h equals, 2 times the square root of 3\"></span> yields the expression <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/84e56657a4ff13893c85a07621ea62e47bd7f1b9aa1162b3dfc775af02c1aa80\" alt=\"one half times, open parenthesis, 8 plus 4, close parenthesis, times, open parenthesis, 2 times the square root of 3, close parenthesis\"></span>, or <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/e2e9b61ba7550105ef0736b9231a47f5d53fe9e29fdaea5645b61edd92058e0c\" alt=\"one half times 12, times, open parenthesis, 2 times the square root of 3, close parenthesis\"></span>, which gives an area of <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/e22b8125e261075830ca9c112aa2d98e51d2a98382003702b06bba3b59f60f5e\" alt=\"12 times the square root of 3 centimeters squared\"></span> for the trapezoid. Since two-thirds of the trapezoid is shaded, the area of the shaded region is <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/518b8319b6338ab02aa47287cb8678a04c873a13a56065b110ae761e874626c4\" alt=\"two thirds times, 12 times the square root of 3, equals, 8 times the square root of 3\"></span>.</p><p>Choice A is incorrect. This is the height of the trapezoid. Choice B is incorrect. This is the area of one of the equilateral triangles, not two. Choice D is incorrect and may result from using a height of 4 for each triangle rather than the height of <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/b71b92a7cb949d0bb099cbabf04ac37f85587db73a7c23bca58fc8453979c5f4\" alt=\"2 times the square root of 3\"></span>.</p><p></p>\n","correct_answer":["C"],"has_media":true,"has_mathml":false,"has_table":false,"source_created_at":"2023-08-02T20:25:59.634000+00:00","source_updated_at":"2023-08-02T20:25:59.634000+00:00","options":[{"label":"A","content_html":"<p class=\"choice_paragraph \">\n            <span class=\"math_expression \">\n              <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/b71b92a7cb949d0bb099cbabf04ac37f85587db73a7c23bca58fc8453979c5f4\" alt=\"2 times the square root of 3\"></span></span>\n          </p>\n","ord":0},{"label":"B","content_html":"<p class=\"choice_paragraph \">\n            <span class=\"math_expression \">\n              <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/763e949e0b327b0b6c87bbe24485ec97e10e8a3f6b282c83c64f325a8186a88c\" alt=\"4 times the square root of 3\"></span></span>\n          </p>\n","ord":1},{"label":"C","content_html":"<p class=\"choice_paragraph \">\n            <span class=\"math_expression \">\n              <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/0b64faf68d164b8f372bfa66abd23b8b71e46296014c55f9ed02a359c5b3536d\" alt=\"8 times the square root of 3\"></span></span>\n          </p>\n","ord":2},{"label":"D","content_html":"<p class=\"choice_paragraph \">\n            <span class=\"math_expression \">\n              <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/16d2e74c7edacf4734ee6e3dc910e4847a0d27f29597d4dce2f5e9f528e2670a\" alt=\"16\"></span></span>\n          </p>\n","ord":3}],"attribution":{"source_id":"cb_question_bank","source_name":"College Board digital SAT question bank (community dump)","rights_holder":"College Board","canonical_url":"https://satsuitequestionbank.collegeboard.org/","retrieved_from":"https://raw.githubusercontent.com/mdn522/sat-question-bank/main/data/cb-digital-questions.json","attribution":"SAT practice questions © College Board, from the official SAT Suite Question Bank. Retrieved via the community dump at github.com/mdn522/sat-question-bank.","disclaimer":"SAT® and PSAT/NMSQT® are trademarks registered by the College Board, which is not affiliated with, does not sponsor, and does not endorse this project.","license":"College Board copyright; source repository carries no licence. Local use only.","redistributable":false,"item_count":2017}}