MCQ
$\left(3 \sin ^2 30^{\circ}-4 \cos ^2 60^{\circ}\right)$ is equal to:
- ✓$-\frac{1}{4}$
- B$\frac{5}{4}$
- C$-\frac{3}{4}$
- D$-\frac{9}{4}$
✓
Answer
Correct option: A.
$-\frac{1}{4}$
$\left(3 \sin ^2 30^{\circ}-4 \cos ^2 60^{\circ}\right)$
$\Rightarrow 3 \times\left(\frac{1}{2}\right)^2-4 \times\left(\frac{1}{2}\right)^2$
$\Rightarrow-\frac{1}{4}$
$\Rightarrow 3 \times\left(\frac{1}{2}\right)^2-4 \times\left(\frac{1}{2}\right)^2$
$\Rightarrow-\frac{1}{4}$
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