Learn how to solve problems step by step online. Prove the trigonometric identity sin(a)^2+1/(1+tan(a)^2)=1. Starting from the left-hand side (LHS) of the identity. Applying the trigonometric identity: 1+\tan\left(\theta \right)^2 = \sec\left(\theta \right)^2. Applying the secant identity: \displaystyle\sec\left(\theta\right)=\frac{1}{\cos\left(\theta\right)}. Divide fractions \frac{1}{\frac{1}{\cos\left(a\right)^2}} with Keep, Change, Flip: a\div \frac{b}{c}=\frac{a}{1}\div\frac{b}{c}=\frac{a}{1}\times\frac{c}{b}=\frac{a\cdot c}{b}.

Prove the trigonometric identity sin(a)^2+1/(1+tan(a)^2)=1