It bascially says when the sum of two angles are 90 deg they are complimentary....
Then it goes on saying
sin(90-theta) = cos theta
and so on.....
I understand the concept such as if sin(30) = cos(60)
But the book doesnt explain why it works.. it just says if two compl angles are 90 deg then sin(90-theta) = cos theta, which is not an explanation at all...
can some one help me understand why this is?