Posted by Katie on Monday, March 5, 2012 at 8:02pm.
Prove (3cosθ4sinθ)^2+(4cosθ+3sinθ)^2=25

Trig  bobpursley, Monday, March 5, 2012 at 8:11pm
square both terms...
9cos^2+4sin^224cossin+16cos^2+24cossin+9sin^2=
9(cos^2+sin^2)+16(cos^2+sin^2)=
and you can finish it.