Question 882823
prove {{{sin^2(theta)=(1-cos2(theta))/2}}}
start with left side:
{{{sin^2(theta)*(2/2)=(sin^2(theta)+sin^2(theta))/2=(1-cos^2(theta)+sin^2(theta))/2
=(1-(cos^2(theta)-sin^2(theta)))/2=(1-cos2(theta))/2}}}