Evaluate the expression 2 tan2 120degree 5 sin2 150degree

Evaluate the expression. 2 tan^2 120degree + 5 sin^2 150degree - cos^2 180degree 2 tan^2 120degree + 5 sin^2 150degree - cos^2 180degree =

Solution

2tan²(120^o)+5sin²(150^o)-cos²(180^o)

=2tan²((90+30)^o)+5sin²((90+60)^o)-cos²(180^o)

=2(-cot(30)^o)²+5(cos(60)^o)²-cos²(180^o)

=2(-3)²+5(1/2)²-(-1)²

=2(3)+5(1/4)-(1)

=6+(5/4)-1

=5+(5/4)

=25/4

=6.25