Question

Is sinx cosx ever equal to 1?

Answer 1

From Pythagorean Identities sin^2x+cos^2x=1
and from that identities we can have sinx+cosx=1, taking sinx=1−cosx and substitute in the equation
sinx+cosx=1
(1−cosx)+cosx=1
Remove the parenthesis
1−cosx+cosx=1
cancel cosx
1=1