If sinA = $$\frac{\text{a}}{\text{b}}$$​, then find the value of cosA.

Correct option is A

Given:
sin A = $$\frac a b$$​​
Formula Used:
$$sin^{2} A + cos^{2} A$$​ = 1
Solution:
​$$sin^{2} A + cos^{2} A$$ = 1​
​$$cos^2 A = 1 - sin^2 A = 1 - \frac {a^2}{ b^2} = \frac {b^2 - a^2} {b^2}$$​​
Therefore,
cos A = $$\sqrt{\frac{b^2 - a^2}{b^2}} = \frac{\sqrt{b^2 - a^2}}{b}$$​​