Question

sin A =a/b then find cos A​

Answer 1

so CosA=

$\frac{ \sqrt{ {b}^{2} - {c}^{2} } }{b}$

HOPE IT HELPS......

Answer 2

sin A = Perpendicular / Hypotenuse

a/b = Perpendicular / Hypotenuse ----(i)

On comparing,

Perpendicular = ax

Hypotenuse = bx

for some value x.

We know,

Hypotenuse² = Perpendicular ² + Base²

(bx)² = (ax)² + Base²

Base² = b²x² - a²x²

Base = x√b² - a²

cos A = Base / Hypotenuse

cos A = x√b² - a² / bx

cancel x

cos A = √b² - a² / b

$\huge{\bold{ \frac{ \sqrt{ b^{2} - a^{2} } }{b} }}$