Question

A is an angle is in the second quadrant and sinA=⅓. find the value of cos A

Answer 1

Answer:

Step-by-step explanation:

cos A is negative whenever A is in the second quadrant.

cos A = sqrt( 1 - (sin A)^2) =

= sqrt( 1 - 1 / 9 ) = sqrt( 8 / 9)

= (2 * sqrt2)/3

Answer 2

Solñ: By HR

Given,SinA=1/3

AB/AC=1/3=k. [Let]

:. AB=k. and AC=3k

Pithagoraous rule,

AC²=AB²+BC²

»BC²=AC²-AB²=(3k)²-k²=(9-1)k²=8k

:. BC=√8k

CosA=BC/AC

=√8k/3k

=√8/3