0When the sum of two angles=90 degrees, they are called complementary angles.
We can use following formula →sin(90-θ)=cosθ,cos(90-θ)=sinθ,tan(90-θ)=cotθ,cosec(90-θ)=secθ,sec(90-θ)=cosecθ
We can apply this to evaluate the following example :-
[cosec^2(90-θ)-tan^2θ]/4(cos248+cos242)
=(sec^2θ-tan^2θ)/4[cos^2(90-42)+cos^2(42)]=1/4(sin^2(42)+cos^2(42))=1/(4x1)=1/4
