Question

If sin θ =3/5, where θ is an acute angle, find the value of cos θ.

Answer 1

`sintheta=3/5`

we know `sin theta="Opposite"/"Hypotunes"=p/h`

`therefore p/h=3/5`                             [∵ Opposite = Perpendicular = p]

p=3k, h=5k

Let the adjacent (base) side be b.

Thus `b=sqrt((5k)^2-(3k)^2)=4k`

`costheta=(4k)/(5k)=4/5`