Question

ccos^4 theta -sin^4 theta is equal to:​

Answer 1

${cos^{4}\theta-sin^{4}\theta}$

= ${(cos^{2}\theta)^{2} - (sin^{2}\theta)^{2}}$

= ${(cos^{2}\theta+sin^{2}\theta)(cos^{2}\theta-sin^{2}\theta}</p><p>= [tex]{1(cos^{2}\theta-sin^{2}\theta)}$

=${(cos^{2}+sin^{2})+2sincos}$

=${2cos\theta\:sin\theta}$