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: $\frac{\sqrt{3}–1}{2\sqrt{2}}$
Correct Answer: $\frac{\sqrt{3}–1}{2\sqrt{2}}$
Solution : Given: $\sin (A–B)=\sin A\cos B–\cos A\sin B$ Let $A=45°$ and $B=30°$ respectively. $\sin (45°–30°)=\sin 45°\cos 30°–\cos 45°\sin 30°$ ⇒ $\sin 15°=\frac{1}{\sqrt{2}}\times \frac{\sqrt{3}}{2}–\frac{1}{\sqrt{2}}\times \frac{1}{2}$ $\therefore \sin 15°=\frac{\sqrt{3}–1}{2\sqrt{2}}$ Hence, the correct answer is $\frac{\sqrt{3}–1}{2\sqrt{2}}$.
Application | Eligibility | Selection Process | Result | Cutoff | Admit Card | Preparation Tips
Question : Given that A and B are second quadrant angles, $\sin A = \frac{1}{3}$ and $\sin B = \frac{1}{5}$, then find the value of $\cos(A-B)$.
Option 1: $\frac{4 \sqrt{3}+1}{15}$
Option 2: $\frac{8 \sqrt{3}-1}{15}$
Option 3: $\frac{8 \sqrt{3}+1}{15}$
Option 4: $\frac{4 \sqrt{3}-1}{15}$
Question : Find the value of $\sqrt{\frac{1-\tan A}{1+\tan A}}$.
Option 1: $\sqrt{\frac{1+\sin 2 A}{\cos 2 A}}$
Option 2: $\sqrt{\frac{1-\sin 2 A}{\cos 2 A}}$
Option 3: $\sqrt{\frac{1+\sin A}{\cos A}}$
Option 4: $\sqrt{\frac{1-\sin A}{\cos A}}$
Question : If $\sin \theta+\cos \theta=\frac{\sqrt{11}}{3}$, then what is $\sin \theta-\cos \theta$?
Option 1: $\frac{\sqrt{7}}{4}$
Option 2: $\frac{\sqrt{7}}{3}$
Option 3: $\frac{\sqrt{5}}{3}$
Option 4: $\frac{\sqrt{5}}{2}$
Question : If $\operatorname{cos} \theta+\operatorname{sin} \theta=\sqrt{2} \operatorname{cos} \theta$, find the value of $(\cos \theta-\operatorname{sin} \theta)$
Option 1: $\sqrt{2} \sin \theta$
Option 2: $\sqrt{2} \cos \theta$
Option 3: $\frac{1}{\sqrt{2}} \sin \theta$
Option 4: $\frac{1}{2}\cos \theta$
Question : If $\sin \theta+\cos \theta=\sqrt{2} \cos \theta$, then find $\frac{\sin \theta-\cos \theta}{\sin \theta}$:
Option 1: $-\sqrt{2}$
Option 2: $-1$
Option 3: $1$
Option 4: $\sqrt{2}$
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile