Question

In applications of trigonometry how do we get to know that in this sum we have to use tan,sin,or cos tita

Answer 1

In any right angled triangle, for any angle θ ,

if our problem involves relation between perpendicular and hypotenuse then we use sin.

Sinθ = the length of the opposite side / the length of the hypotenuse = p / h

similarly,

if our problem involves relation between base and hypotenuse then we use cos.

Cos θ = the length of the adjacent side/ the length of the hypotenuse = b / h

and if our problem involves relation between perpendicuar and base then we use tan.

Tan θ = the length of the opposite side./ the length of the adjacent side = p / b