Question

The value of $si{n}^2{30}^{\circ }$ - $co{s}^2{30}^{\circ }$ is:

• A. $-\frac{1}{2}$
• B. $\frac{\sqrt{3}}{2}$
• C. $\frac{3}{2}$
• D. $\frac{2}{3}$

Answer 1

Answer: (A)

$-\frac{1}{2}$

${\sin }^{2}30°-{\cos }^{2}30°$

$={\left(\frac{1}{2}\right)}^2-{\left(\frac{\sqrt{3}}{2}\right)}^2$

$=\frac{1}{4}-\frac{3}{4}$

$=-\frac{2}{4}$

$=-\frac{1}{2}$

Hence, the answer is $-\frac{1}{2}.$