Given the value of cos 50° ? 0.6428, enter the sine of a complementary angle. Use an expression relating trigonometric ratios of complementary angles.

sin 40° = 0.6428

Step-by-step explanation:

The complementary ratio of sine is cos and vice-versa.

sin θ = cos (90 - θ)

cos θ = sin (90 - θ)

So cos 50° = sin (90 - 50)°

                   = sin 40°

sin 40° = 0.6428

This indicates that the complement of cos 50° is sin 40° which is equal to 0.6428.

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step-by-step explanation: