Question

if sinA=a/b then cosA=?​

Answer 1

$sinA = \frac{a}{b} \\ \\ = > cosA = \sqrt{1 - { \sin}^{2}A} \\ \\ = \sqrt{1 - { (\frac{a}{b}) }^{2} } \\ \\ = \sqrt{1 - \frac{ {a}^{2} }{ {b}^{2} } } \\ \\ = \sqrt{ \frac{ {b}^{2} - {a}^{2} }{ {b}^{2} } } \\ \\ = \frac{ \sqrt{ {b}^{2} - {a}^{2} } }{b}$

I hope this helps you.

Answer 2

Answer:

H²=P²+B²= (bk)²=(ak)²+B² = B²= k²(b²-a²)

B=k√(b²-a²)

cosA= k√(b²-a²)/bk = √(b²-a²)/b