1.In right triangle ABC with right angle at C, leg AC (adjacent to angle A) = 15 cm and hypotenuse AB = 17 cm. What is the value of cos(A)?
A8 / 17
B15 / 17
C15 / 8
D8 / 15
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Grade 10geometryOriginal practice
Geometry & Trigonometry: SOH CAH TOA & Right Triangles
Calculate sine, cosine, and tangent ratios, solve for unknown sides and acute angles, and apply angles of elevation in authentic right triangle problems.
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Sheet 143D7943 · questions and answers share this ID
About this practice
Grade 10 · math · Matching answer key included · US Letter and A4
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Teaching guide, sample answers and curriculum references
Before you begin
Identify the hypotenuse and distinguish opposite and adjacent sides relative to a marked acute angle.
How to use this worksheet
- Model the target skill: define trigonometric ratios (sine, cosine, tangent) for acute angles in right triangles using SOH-CAH-TOA. Use the first task as a guided example before asking for an independent response.
- Check readiness first: Identify the hypotenuse and distinguish opposite and adjacent sides relative to a marked acute angle.
- Discuss an incorrect response using this distinction: Opposite and adjacent depend on the chosen angle; the hypotenuse stays opposite the right angle.
A common mistake to discuss
Opposite and adjacent depend on the chosen angle; the hypotenuse stays opposite the right angle.
What to practice next
Label sides for a different acute angle before selecting sine, cosine or tangent.
Sample question and answer
In right triangle ABC with right angle at C, leg AC (adjacent to angle A) = 15 cm and hypotenuse AB = 17 cm. What is the value of cos(A)?
- A. 8 / 17
- B. 15 / 17
- C. 15 / 8
- D. 8 / 15
Answer: B. By definition of cosine (CAH): cos(A) = Adjacent / Hypotenuse = AC / AB = 15 / 17.
Intended curriculum references: CCSS.MATH.CONTENT.HSG.SRT.C.6 · CCSS.MATH.CONTENT.HSG.SRT.C.8. These references describe learning goals; they are not endorsements.
Published 2026-10-02; updated 2026-10-02. Original MakeWorksheet practice. Automated consistency checks support publication; independent subject-specialist review is not recorded. Read our editorial policy.
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