Question

Find (cos 5◦+ isin 5◦) (cos 20◦+ isin 20◦)and write the result in trigonometric form.

Answer 1

(cos(5)+i*sin(5))(cos(20)+i*sin(20))


(e^(5i))*(e^(20i))


e^(5i+20i)


e^(25i)


cos(25) + i*sin(25)


So (cos(5)+i*sin(5))(cos(20)+i*sin(20)) = cos(25) + i*sin(25)