Question

if sin equals to 3 by 4 then calculate Cos A

Answer 1

we are given sine a is equal to 3 over 4 that is side opposite to angle a over hypotenuse. and this is equal to opposite to angle a is BC and hypotenuse is AC. ... we shall find cos a it will be equal to side adjacent to angle a over hypotenuse.

Answer 2

$\sin( \alpha ) = \frac{3}{4}$
hence we can write sinα= opposite side/hypotenuse
comparing this with above fraction
Opposite side = 3x
Hypotenuse = 4x
so adj side by Pythagorean theorem =√7x
cosα= adj side/hypotenuse
$\cos( \alpha ) = \frac{ \sqrt{7} }{4}$