Question 285400
1. If sin(theta)=1/2, then sin(-theta)= -1/2,
--- 
sin(pi - theta)= sin(pi)cos(theta)-cos(pi)sin(theta) = 0-(-1)(1/2) = 1/2
---  
sin(theta + pi)= sin(theta)cos(pi)+cos(theta)sin(pi) = -sin(theta)+0 = -1/2
==============================================================

2. If cos(theta)=(sqrt3)/2, then cos(-theta)=(sqrt3)/2,
--- 
cos(pi - theta)= cos(pi)cos(theta)+sin(pi)sin(theta)= -cos(theta)= -(sqrt3)/2
---- 
cos(theta+pi)=cos(theta)cos(pi)-sin(theta)sin(pi)=-cos(theta)= -(sqrt3)/2
==================================
Cheers,
Stan H.