Question : In $\triangle ABC, \angle B=90^{\circ}$ and AB : BC = 1 : 2. The value of $\cos A+\tan C$ is:
Option 1: $\frac{5+\sqrt{5}}{2 \sqrt{5}}$
Option 2: $\frac{1+\sqrt{5}}{2 \sqrt{5}}$
Option 3: $\frac{2 \sqrt{5}}{2+\sqrt{5}}$
Option 4: $\frac{2+\sqrt{5}}{2 \sqrt{5}}$
Correct Answer: $\frac{2+\sqrt{5}}{2 \sqrt{5}}$
Solution : In $\triangle ABC, \angle B=90^{\circ}$ AB : BC = 1 : 2 ⇒ $\frac{\text{AB}}{\text{BC}} = \frac{1}{2}$ ⇒ $\frac{\text{AB}}{1} = \frac{\text{BC}}{2}=$ k ⇒ AB = k, BC = 2k Using the Pythagoras theorem, AC$^2$ = BC$^2$ + AB$^2$ = (2k)$^2$ + k$^2$ = 5k$^2$ So, AC = $\sqrt{5}$k By definition of trigonometric ratios, $\cos A = \frac{\text{AB}}{\text{AC}} = \frac{1}{\sqrt{5}}$ $\tan C = \frac{\text{AB}}{\text{BC}} = \frac{1}{2}$ ⇒ $\cos A+\tan C$ = $ \frac{1}{2}+ \frac{1}{\sqrt{5}}$ = $\frac{\sqrt{5}+2}{2 \sqrt{5}}$ Hence, the correct answer is $\frac{2+\sqrt{5}}{2 \sqrt{5}}$.
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Question : If $4-2 \sin ^2 \theta-5 \cos \theta=0,0^{\circ}<\theta<90^{\circ}$, then the value of $\cos \theta-\tan \theta$ is:
Option 1: $\frac{1+2 \sqrt{3}}{2}$
Option 2: $\frac{2-\sqrt{3}}{2}$
Option 3: $\frac{2+\sqrt{3}}{2}$
Option 4: $\frac{1-2 \sqrt{3}}{2}$
Question : If $4-2 \sin ^2 \theta-5 \cos \theta=0,0^{\circ}<\theta<90^{\circ}$, then the value of $\cos \theta+\tan \theta$ is:
Option 1: $\frac{2-\sqrt{3}}{2}$
Option 2: $\frac{1+2 \sqrt{3}}{2}$
Question : In a triangle ABC, if $\angle B=90^{\circ}, \angle C=45^{\circ}$ and AC = 4 cm, then the value of BC is:
Option 1: $\sqrt{2} \mathrm{~cm}$
Option 2: $4 \mathrm{~cm}$
Option 3: $2 \sqrt{2} \mathrm{~cm}$
Option 4: $4 \sqrt{2} \mathrm{~cm}$
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 : Find the value of $\frac{\sin ^2 39^{\circ}+\sin ^2\left(90^{\circ}–39^{\circ}\right)}{\cos ^2 35^{\circ}+\cos ^2\left(90^{\circ}–35^{\circ}\right)}+3 \tan 25^{\circ} \tan 75^{\circ}$:
Option 1: 2
Option 2: 4
Option 3: 3
Option 4: 1
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