2024 · Q100
In a right triangle, ABC ∠A = 90° and AD is perpendicular to BC. If ∠CAD = 60° and BC = 6 cm, then what is AB equal to?
Elementary MathematicsGeometry: Lines, Angles and Triangles
- A3 cm
- B4 cm
- C5 cm
- D6 cm
Explanation
In ΔADC, ∠D = 90° and ∠CAD = 60° give ∠C = 30°. In ΔABC right-angled at A, the side AB is opposite the 30° angle at C. Thus AB = BC × sin30° = 6 × ½ = 3 cm — option A.