In triangle ABC, ∠B = 90°, and AB = 12 cm, AC = 13 cm. Find the value of sin A + cos A.
Show answer & explanation
Correct answer: C
Explanation
Given:
∠B = 90°
AB = 12 cm
AC = 13 cm
By the formula:
AC² = AB² + BC²
sinA = opposite side / hypotenuse
cosA = adjacent side / hypotenuse
13² = 12² + BC²
169 = 144 + BC²
BC² = 25
BC = 5
sinA = 5/13
cosA = 12/13
sinA + cosA= 5/13 + 12/13= 17/13