Question : The value of the expression $\cos ^2 45^{\circ}+\cos ^2 135^{\circ}+\cos ^2 225^{\circ}+\cos ^2 315^{\circ}$ is:
Option 1: $2$
Option 2: $\frac{1}{2}$
Option 3: $\frac{3}{2}$
Option 4: $1$
Correct Answer: $2$
Solution : Here, we have : $\cos^245^\circ = (\frac{1}{\sqrt{2}})^2 = \frac{1}{2}$ $\cos^2135^\circ = \cos^2(90^\circ + 45^\circ ) = -\sin^245^\circ = (-\frac{1}{\sqrt{2}})^2 = \frac{1}{2}$ $\cos^2225^\circ = \cos^2(180^\circ + 45^\circ ) = -\cos^245^\circ = (-\frac{1}{\sqrt{2}})^2 = \frac{1}{2}$ $\cos^2315^\circ = \cos^2(360^\circ -45^\circ ) = \cos^245^\circ = (\frac{1}{\sqrt{2}})^2 = \frac{1}{2}$ $\cos^245^\circ + \cos^2135^\circ + \cos^2225^\circ + \cos^2315^\circ = ( \frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}) = 2$ Hence, the correct answer is 2.
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Question : The value of $\frac{\sin ^2 30^{\circ}+\cos ^2 60^{\circ}+\sec 45^{\circ} × \sin 45^{\circ}}{\sec 60^{\circ}+{\text{cosec}} 30^{\circ}}$ is:
Option 1: $\frac{1}{4}$
Option 2: $-\frac{3}{8}$
Option 3: $\frac{3}{8}$
Option 4: $-\frac{1}{4}$
Question : The value of $\frac{\sin ^2 52^{\circ}+2+\sin ^2 38^{\circ}}{4 \cos ^2 43^{\circ}-5+4 \cos ^2 47^{\circ}}$ is:
Option 1: $3$
Option 2: $\frac{1}{3}$
Option 3: $-\frac{1}{3}$
Option 4: $-3$
Question : Which of the following is the value of $\sqrt{\frac{1-\sin 45^{\circ}}{1+\sin 45^{\circ}}}$?
Option 1: $\cos 45^{\circ} - \tan 45^{\circ}$
Option 2: $\tan 45^{\circ} - \sec 45^{\circ}$
Option 3: $\tan 45^{\circ}$
Option 4: $\sec 45^{\circ} - \tan 45^{\circ}$
Question : Find the value of $\frac{\cos 65^{\circ}}{\sin 25^{\circ}}+\frac{5 \sin 19^{\circ}}{\cos 71^{\circ}}-\frac{3 \cos 28^{\circ}}{\sin 62^{\circ}}$.
Option 1: 2
Option 2: 0
Option 3: 1
Option 4: 3
Question : The value of $\frac{\sin ^2 30^{\circ}+\cos ^2 60^{\circ}-\sec 35^{\circ} \cdot \sin 55^{\circ}}{\sec 60^{\circ}+\operatorname{cosec} 30^{\circ}}$ is equal to:
Option 1: $\frac{1}{8}$
Option 2: $-\frac{1}{4}$
Option 3: $\frac{1}{4}$
Option 4: $-\frac{1}{8}$
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