Question

sin(x )+ sin(y )+ sin(z )= 3;: then evaluate cos(x )+ cos(y )+ cos(z)

Answer 1

Whatever the ranges of angle x , y and z are , the value of sine function always lie in the interval [ - 1 , 1 ] .Hence , sin x + sin y + sin z = 3 is possible only when sin x = sin y = sin z = 1 then x = y = z = 90

Therefore , cos 90 + cos 90 + cos 90 = 0