## Trigonometry (11th Edition) Clone

$-i$
Step 1: $i^{15}=i^{14+1}=i^{14}\times i$=$(i^{2})^{7}\times i$ Step 2: As $i^{2}=-1$, $(i^{2})^{7}\times i=(-1)^{7}\times i=-1\times i=-i$