Question : What is the value of $3 \sin ^2 30^{\circ}+\frac{3}{5} \cos ^2 60^{\circ}–2 \sec ^2 45^{\circ} $?
Option 1: $-\frac{5}{2}$
Option 2: $-\frac{5}{8}$
Option 3: $-\frac{31}{10}$
Option 4: $-\frac{25}{17}$
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Correct Answer: $-\frac{31}{10}$
Solution : Given: The trigonometric expression is $3 \sin ^2 30^{\circ}+\frac{3}{5} \cos ^2 60^{\circ}–2 \sec ^2 45^{\circ} $. We know the values of trigonometric ratios, $\sin 30^{\circ} =\frac{1}{2}$, $\cos 60^{\circ}=\frac{1}{2}$ and $\sec 45^{\circ}=\sqrt2$. ⇒ $3 \sin ^2 30^{\circ}+\frac{3}{5} \cos ^2 60^{\circ}–2 \sec ^2 45^{\circ}$ $= 3\times(\frac{1}{2})^2+\frac{3}{5}\times(\frac{1}{2})^2–2 \times (\sqrt2)^2 $ $= \frac{3}{4}+\frac{3}{20}-4=\frac{15+3-80}{20}$ $= \frac{18-80}{20}=-\frac{62}{20}=-\frac{31}{10}$ Hence, the correct answer is $-\frac{31}{10}$.
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Question : The value of $\frac{5 \cos ^2 60^{\circ}+4 \sec ^2 30^{\circ}-\tan ^2 45^{\circ}}{\tan ^2 60^{\circ}-\sin ^2 30^{\circ}-\cos ^2 45^{\circ}}$ is:
Option 1: $\frac{67}{27}$
Option 2: $\frac{22}{9}$
Option 3: $\frac{67}{24}$
Option 4: $\frac{19}{9}$
Question : What will be the value of $\frac{\sin 30^{\circ} \sin 40^{\circ} \sin 50^{\circ} \sin 60^{\circ}}{\cos 30^{\circ} \cos 40^{\circ} \cos 50^{\circ} \cos 60^{\circ}}$?
Option 1: $\frac{1}{\sqrt{2}}$
Option 2: $\sqrt{3}$
Option 3: $1$
Option 4: $\frac{1}{\sqrt{3}}$
Question : If $x\sin ^{2}60^{\circ}-\frac{3}{2}\sec 60^{\circ}\tan^{2}30^{\circ}+\frac{4}{5}\sin ^{2}45^{\circ}\tan ^{2}60^{\circ}=0$, then $x$ is:
Option 1: $-\frac{1}{15}$
Option 2: $–4$
Option 3: $-\frac{4}{15}$
Option 4: $–2$
Question : The value of $\cos^{2}30^{\circ}+\sin^{2}60^{\circ}+\tan^{2}45^{\circ}+\sec^{2}60^{\circ}+\cos0^{\circ}$ is:
Option 1: $4\frac{1}{2}$
Option 2: $5\frac{1}{2}$
Option 3: $6\frac{1}{2}$
Option 4: $7\frac{1}{2}$
Question : The value of $\left(\sin 30^{\circ} \cos 60^{\circ}-\cos 30^{\circ} \sin 60^{\circ}\right)$ is equal to:
Option 1: $-\cos 30^{\circ}$
Option 2: $-\sin 30^{\circ}$
Option 3: $\cos 30^{\circ}$
Option 4: $\sin 30^{\circ}$
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