Tow boys raising a buket pull it at an angle ` theta` to each ogher. If each exerts a force of `20 N` and their effective pull is `30 N`, what is the angle ` theta` between their arms ?

Explanation

Here, ` A= 20 N , B= 20 N , R = 30 theta= ?`
using ` R= sqrt (A^2 + B^2 + 2 AB cos theta)` ltBrgt wh have, ` 30^2 = 20^2 + 2 xx 20 xx 20 cos theta`
or ` cos theta ( 30^2 - 20^2 - 20^2)/(2 xx 20 xx 20) =0. 125`
or ` theta = 82^2 49'` .