Trig
posted by Katie .
Prove (3cosθ4sinθ)^2+(4cosθ+3sinθ)^2=25

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.
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