Question : If A is an acute angle and cot A + cosec A = 3, then the value of sin A is:
Option 1: $1$
Option 2: $\frac{3}{5}$
Option 3: $\frac{4}{5}$
Option 4: $0$
Correct Answer: $\frac{3}{5}$
Solution : Given: cot A + cosec A = 3.....................(1) By using the identities: cosec2A – cot2A = 1 ⇒ (cosec A + cot A) (cosec A – cot A) = 1 ⇒ cosec A – cot A = $\frac{1}{3}$....................(2) On adding both equations, we get: ⇒ 2cosec A = 3 + $\frac{1}{3}$ = $\frac{10}{3}$ ⇒ cosec A = $\frac{10}{3×2}$ = $\frac{5}{3}$ ⇒ sin A = $\frac{3}{5}$ Hence, the correct answer is $\frac{3}{5}$.
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Question : The value of $\frac{\sin A}{\cot A+\operatorname{cosec} A}-\frac{\sin A}{\cot A-\operatorname{cosec} A}+1$ is:
Option 1: $\frac{1}{2}$
Option 2: $3$
Option 3: $0$
Option 4: $2$
Question : If $\theta$ is an acute angle and $\sin \theta+\operatorname{cosec} \theta=2$, then the value of $\sin ^5 \theta+\operatorname{cosec}^5 \theta$ is:
Option 1: 10
Option 2: 2
Option 3: 4
Option 4: 5
Question : If $\alpha$ is an acute angle and $2\sin \alpha+15\cos^2\alpha=7$, then the value of $\cot \alpha$ is:
Option 1: $\frac{4}{3}$
Option 2: $\frac{4}{5}$
Option 3: $\frac{5}{4}$
Option 4: $\frac{3}{4}$
Question : If $\operatorname{cosec} A+\cot A=3$, $0 \leq A \leq 90^{\circ}$, then find the value of cos A.
Option 1: $\frac{3}{4}$
Option 2: $\frac{2}{5}$
Option 3: $\frac{3}{5}$
Option 4: $\frac{4}{5}$
Question : If $\sin A=\frac{\sqrt{3}}{2}, 0<A<90^{\circ}$, then find the value of $2(\operatorname{cosec} A + \cot A)$.
Option 1: $2 \sqrt{3}$
Option 2: $\sqrt{3}$
Option 3: $\frac{2}{\sqrt{3}}$
Option 4: $\frac{1}{\sqrt{3}}$
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