From the de Moivre's we have,
<span>
(cosθ+isinθ)^n=cos(nθ)+isin(nθ)
</span><span>
Therefore,
</span><span>
R((cosθ+isinθ)^5)=cos(5θ)I((cosθ+isinθ)^5)=sin(5θ)
</span><span>
Simplifying,
</span><span>
cos^5(θ)−10(sin^2(θ))(cos^3(θ))+5(sin^4(θ))(cosθ)=cos(5θ) </span><span>
</span>
Answer:
b
Step-by-step explanation:
Answer:
38°
Step-by-step explanation:
∠4=∠2
∠2=∠6
∠6=38°
So ∠4=38°