Question

Find B
............​

Answer 1

Given:

In ΔABC, AB = 5 unit, BC = 2 unit and ∠C = 90°

To find the The value of ∠B.

Formula

By Trigonometric Ratio we know,

$cos \ \theta=\frac{adj}{hyp}$

Let us take ∠B = θ

With respect to θ, BC is the adjacent side and AB is the hypotenuse.

So,

$cos \ \theta=\frac{BC}{AB}$

$cos \ B=\frac{2}{5}$

     $B=cos^{-1} (\frac{2}{5} )$

     $B = 66.42^{\circ}$

Hence, the value of ∠B is 66.42°.