Question : The value of (1+ sin4 A – cos4 A) cosec2 A is:
Option 1: –2
Option 2: 2
Option 3: 1
Option 4: –1
Correct Answer: 2
Solution : (1+ sin4 A – cos4 A) cosec2 A = [1+ (sin2 A)2 – (cos2 A)2] cosec2 A = [1+ (sin2 A + cos2 A)(sin2 A – cos2 A)] cosec2 A = [1+ sin2 A – cos2 A] cosec2 A = [ sin2 A + (1– cos2 A)] cosec2 A = [ sin2 A + sin2 A ] cosec2 A = 2sin2 A × cosec2 A = 2 Hence, the correct answer is 2.
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Question : What is the value of the following in terms of trigonometric ratios? $\frac{\sin A}{1+\cos A}+\frac{1+\cos A}{\sin A}$
Option 1: $2\operatorname{cosec A}$
Option 2: $2\operatorname{cos A}$
Option 3: $2\operatorname{sec A}$
Option 4: $2\operatorname{sin A}$
Question : Find the value of $\sin (50^{\circ} + A) – \cos (40^{\circ} - A)$.
Option 1: 2
Option 2: 0
Option 3: –1
Option 4: 1
Question : If $\sin A+\sin ^2 A=1$, then the value of $\cos ^4 A+\cos ^6 A$ is:
Option 1: $\cos A$
Option 2: $\sin A$
Option 4: 0
Question : If a3 + b3 = 217 and a + b = 7, then the value of ab is:
Option 1: – 6
Option 2: – 1
Option 3: 7
Option 4: 6
Question : If $\sin (A-B)=\sin A \cos B–\cos A\sin B$, then $\sin 15°$ will be:
Option 1: $\frac{\sqrt{3}+1}{2\sqrt{2}}$
Option 2: $\frac{\sqrt{3}}{2\sqrt{2}}$
Option 3: $\frac{\sqrt{3}–1}{–\sqrt{2}}$
Option 4: $\frac{\sqrt{3}–1}{2\sqrt{2}}$
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