{"id":"cb_question_bank:7d93ab48-f21d-4f63-809d-054c50ef9739","source_id":"cb_question_bank","source_item_id":"7d93ab48-f21d-4f63-809d-054c50ef9739","external_id":"16428dd4-6b32-4580-ace2-d2dbf0505a76","ibn":null,"question_id":"568d66a7","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":"An isosceles right triangle has a perimeter of 94 plus 94 StartRoot 2 EndRoot inches. What is the length, in inches, of one leg of this triangle?","stimulus":"","stimulus_html":null,"stem_html":"<p style=\"text-align: left;\">An isosceles right triangle has a perimeter of <math alttext=\"94 plus 94 StartRoot 2 EndRoot\"><mrow>\n\t<mn>94</mn>\n\t<mo>+</mo>\n\t<mrow>\n\t\t<mn>94</mn>\n\t\t<msqrt>\n\t\t\t<mn>2</mn>\n\t\t</msqrt>\n\t</mrow>\n</mrow>\n</math> inches. What is the length, in inches, of one leg of this triangle?</p>","rationale_html":"<p style=\"text-align: left;\">Choice B is correct. It's given that the right triangle is isosceles. In an isosceles right triangle, the two legs have equal lengths, and the length of the hypotenuse is <math alttext=\"StartRoot 2 EndRoot\"><msqrt>\n\t<mn>2</mn>\n</msqrt>\n</math> times the length of one of the legs. Let&nbsp;<math alttext=\"script l\"><mi>l</mi></math> represent the length, in inches, of each leg of the isosceles right triangle. It follows that the length of the hypotenuse is <math alttext=\"script l StartRoot 2 EndRoot\"><mi>l</mi><msqrt><mn>2</mn></msqrt></math> inches. The perimeter of a figure is the sum of the lengths of the sides of the figure. Therefore, the perimeter of the isosceles right triangle is&nbsp;<math alttext=\"script l plus script l plus script l StartRoot 2 EndRoot\"><mi>l</mi><mo>+</mo><mi>l</mi><mo>+</mo><mi>l</mi><msqrt><mn>2</mn></msqrt></math> inches. It's given that the perimeter of the triangle is&nbsp;<math alttext=\"94 plus 94 StartRoot 2 EndRoot\"><mn>94</mn><mo>+</mo><mn>94</mn><msqrt><mn>2</mn></msqrt></math> inches. It follows that&nbsp;<math alttext=\"script l plus script l plus script l StartRoot 2 EndRoot equals 94 plus 94 StartRoot 2 EndRoot\"><mi>l</mi><mo>+</mo><mi>l</mi><mo>+</mo><mi>l</mi><msqrt><mn>2</mn></msqrt><mo>=</mo><mn>94</mn><mo>+</mo><mn>94</mn><msqrt><mn>2</mn></msqrt></math>. Factoring the left-hand side of this equation yields <math alttext=\"left parenthesis 1 plus 1 plus StartRoot 2 EndRoot right parenthesis script l equals 94 plus 94 StartRoot 2 EndRoot\"><mfenced><mrow><mn>1</mn><mo>+</mo><mn>1</mn><mo>+</mo><msqrt><mn>2</mn></msqrt></mrow></mfenced><mi>l</mi><mo>=</mo><mn>94</mn><mo>+</mo><mn>94</mn><msqrt><mn>2</mn></msqrt></math>, or&nbsp;<math alttext=\"left parenthesis 2 plus StartRoot 2 EndRoot right parenthesis script l equals 94 plus 94 StartRoot 2 EndRoot\"><mfenced><mrow><mn>2</mn><mo>+</mo><msqrt><mn>2</mn></msqrt></mrow></mfenced><mi>l</mi><mo>=</mo><mn>94</mn><mo>+</mo><mn>94</mn><msqrt><mn>2</mn></msqrt></math>. Dividing both sides of this equation by&nbsp;<math alttext=\"2 plus StartRoot 2 EndRoot\"><mn>2</mn><mo>+</mo><msqrt><mn>2</mn></msqrt></math> yields <math alttext=\"script l equals StartFraction 94 plus 94 StartRoot 2 EndRoot Over 2 plus StartRoot 2 EndRoot EndFraction\"><mi>l</mi><mo>=</mo><mfrac><mrow><mn>94</mn><mo>+</mo><mn>94</mn><msqrt><mn>2</mn></msqrt></mrow><mrow><mn>2</mn><mo>+</mo><msqrt><mn>2</mn></msqrt></mrow></mfrac></math>. Rationalizing the denominator of the right-hand side of this equation by multiplying the right-hand side of the equation by <math alttext=\"StartFraction 2 minus StartRoot 2 EndRoot Over 2 minus StartRoot 2 EndRoot EndFraction\"><mfrac><mrow><mn>2</mn><mo>-</mo><msqrt><mn>2</mn></msqrt></mrow><mrow><mn>2</mn><mo>-</mo><msqrt><mn>2</mn></msqrt></mrow></mfrac></math> yields <math alttext=\"script l equals StartFraction left parenthesis 94 plus 94 StartRoot 2 EndRoot right parenthesis left parenthesis 2 minus StartRoot 2 EndRoot right parenthesis Over left parenthesis 2 plus StartRoot 2 EndRoot right parenthesis left parenthesis 2 minus StartRoot 2 EndRoot right parenthesis EndFraction\"><mi>l</mi><mo>=</mo><mfrac><mrow><mfenced><mrow><mn>94</mn><mo>+</mo><mn>94</mn><msqrt><mn>2</mn></msqrt></mrow></mfenced><mfenced><mrow><mn>2</mn><mo>-</mo><msqrt><mn>2</mn></msqrt></mrow></mfenced></mrow><mrow><mfenced><mrow><mn>2</mn><mo>+</mo><msqrt><mn>2</mn></msqrt></mrow></mfenced><mfenced><mrow><mn>2</mn><mo>-</mo><msqrt><mn>2</mn></msqrt></mrow></mfenced></mrow></mfrac></math>. Applying the distributive property to the numerator and to the denominator of the right-hand side of this equation yields&nbsp;<math alttext=\"script l equals StartFraction 188 minus 94 StartRoot 2 EndRoot plus 188 StartRoot 2 EndRoot minus 94 StartRoot 4 EndRoot Over 4 minus 2 StartRoot 2 EndRoot plus 2 StartRoot 2 EndRoot minus StartRoot 4 EndRoot EndFraction\"><mi>l</mi><mo>=</mo><mfrac><mrow><mn>188</mn><mo>-</mo><mn>94</mn><msqrt><mn>2</mn></msqrt><mo>+</mo><mn>188</mn><msqrt><mn>2</mn></msqrt><mo>-</mo><mn>94</mn><msqrt><mn>4</mn></msqrt></mrow><mrow><mn>4</mn><mo>-</mo><mn>2</mn><msqrt><mn>2</mn></msqrt><mo>+</mo><mn>2</mn><msqrt><mn>2</mn></msqrt><mo>-</mo><msqrt><mn>4</mn></msqrt></mrow></mfrac></math>. This is equivalent to&nbsp;<math alttext=\"script l equals StartFraction 94 StartRoot 2 EndRoot Over 2 EndFraction\"><mi>l</mi><mo>=</mo><mfrac><mrow><mn>94</mn><msqrt><mn>2</mn></msqrt></mrow><mn>2</mn></mfrac></math>, or&nbsp;<math alttext=\"script l equals 47 StartRoot 2 EndRoot\"><mi>l</mi><mo>=</mo><mn>47</mn><msqrt><mn>2</mn></msqrt></math>. Therefore, the length, in inches, of one leg of the isosceles right triangle is <math alttext=\"47 StartRoot 2 EndRoot\"><mrow>\n\t<mn>47</mn>\n\t<msqrt>\n\t\t<mn>2</mn>\n\t</msqrt>\n</mrow>\n</math>.</p>\n<p style=\"text-align: left;\">Choice A is incorrect and may result from conceptual or calculation errors.</p>\n<p style=\"text-align: left;\">Choice C is incorrect. This is the length, in inches, of the hypotenuse.</p>\n<p style=\"text-align: left;\">Choice D is incorrect and may result from conceptual or calculation errors.</p>","correct_answer":["B"],"has_media":false,"has_mathml":true,"has_table":false,"source_created_at":"2023-08-02T20:25:59.840000+00:00","source_updated_at":"2023-08-02T20:25:59.840000+00:00","options":[{"label":"A","content_html":"<p><math alttext=\"47\"><mn>47</mn>\n</math></p>","ord":0},{"label":"B","content_html":"<p><math alttext=\"47 StartRoot 2 EndRoot\"><mrow>\n\t<mn>47</mn>\n\t<msqrt>\n\t\t<mn>2</mn>\n\t</msqrt>\n</mrow>\n</math></p>","ord":1},{"label":"C","content_html":"<p><math alttext=\"94\"><mn>94</mn>\n</math></p>","ord":2},{"label":"D","content_html":"<p><math alttext=\"94 StartRoot 2 EndRoot\"><mrow>\n\t<mn>94</mn>\n\t<msqrt>\n\t\t<mn>2</mn>\n\t</msqrt>\n</mrow>\n</math></p>","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}}