Question

( cos ^{2} alpha-sin ^{2} alpha=tan ^{2} beta cdot pi )
( frac{1 beta}{b text { th side }} )
( begin{aligned} cos ^{2} alpha &-sin ^{2} alpha-1=frac{sin ^{2} beta}{cos ^{2} beta}-1 &-2 sin ^{2} alpha=frac{sin ^{2} beta-cos ^{2} beta}{cos ^{2} beta} &=frac{2 sin ^{2} alpha}{sec ^{2} beta}=sin ^{2} beta-cos ^{2} beta end{aligned} )
( frac{sin ^{2} alpha}{cos ^{2} alpha+sin ^{2} alpha}=sin ^{2} beta-cos ^{2} betaleft[frac{-2 sin ^{2} alpha}{1+tan ^{2} beta}=sin ^{2} beta-cos ^{2} betaright. )
( =cos ^{2} beta cdot sin ^{2} beta mid< )
7
( tan ^{2} alpha=cos ^{2} beta-sin ^{2} beta )

# If cos2 a - sinº a = tan’B, show that cos- sinB = tan a

Solution