Question

If sin m° = 0.5, which of the following is the value of cos m°?

A. 0.85
B. 0.87
C. 0.78
D. 0.67

Answer 1

If $\sin m{}^{\circ} = 0.5$, which of the following is the value of $\cos m{}^{\circ}$?

A. 0.85

B. 0.87

C. 0.78

D. 0.67

**Solution:**

We'll determine $\cos m{}^{\circ}$, applying the Pythagorean trigonometric identity:

$$\cos^2 m + \sin^2 m = 1$$ $$\cos^2 m = 1 - \sin^2 m$$ $$\cos^2 m = 1 - \left(\frac{1}{2}\right)^2$$ $$\cos^2 m = \frac{3}{4}$$ $$\cos m = \frac{\sqrt{3}}{2}$$ $$\cos m = 0.87$$

**Answer:** B 0.87