Question

show that cos135°sin45°-sin135cos45°+cos180°=-2

Answer 1

hope i help you ....

Answer 2

Using the identity,
sin(A-B) = sinAcosB - CosAsinB,

cos135sin45 - sin135cos45 = sin(45-135) = sin(-90) = -1

We know cos180 = -1
Therefore answer is -1 -1 = -2