What does cos(arctan((-3pi)/4)) cos(arctan(3π4)) equal?

1 Answer

cos(arctan((-3pi)/4))=4/sqrt(16+9pi^2)cos(arctan(3π4))=416+9π2

Explanation:

We are looking for the cosine function of an angle A. The angle A whose tangent =(-3pi)/43π4

A=arctan((-3pi)/4)A=arctan(3π4) it is an angle

Just imagine a right triangle with angle A with opposite side =-3pi=3π
and with adjacent side =4=4. Then we have a hypotenuse =sqrt(4^2+(-3pi)^2)=sqrt(16+9pi^2)=42+(3π)2=16+9π2

cos A=4/sqrt(16+9pi^2)cosA=416+9π2