Prove that in a triangle ABC,:

sin(A)sin(B)sin(C) + cos(A)cos(B) = 1

implies:

A = B = 45° and C = 90°.

(In reply to A start... by Brian Wainscott)

Next thing you could do is use the identity sine squared of x times cosine squared of x is equall to 1. Thus, since A=B it can be simplified to sine squared of A times sin(C) + cosine squared of A is equal to 1. Since C=90 the sine of 90 is 1 so that can be taken out and you are left with the indentity.

Posted by TCNZ on 2004-06-16 18:21:59