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