Question

Find Value of cos(-2070°).

Answer 1

cos(-2070°)=cos(2070°)

cos(22*90°+90°)=

cos(90°)=

0

Answer 2

Answer:

cos(-2070°)=0.

Step-by-step explanation:

Given:  cos(-2070°).

To find the value.

We know that, cos(-x) = cosx.

=> cos(-2070°) = cos(2070°).

=> cos(2070°) = cos(10$\pi$+270°)

                       = cos(270°)        [cos(2$\pi$+$\theta$)=cos$\theta$]

                       = cos(180°+90° )

                       = cos(90°)          [cos($\pi+\theta$)=cos$\theta$]

                       =0

Therefore, cos(-2070°)= 0.

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