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RRB Technician Grade 1 Model Paper 1

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Question : 55 of 100

Marks: +1, -0

\frac{sin18^{∘}}{cos72^{∘}}+\frac{tan26^{∘}}{cot64^{∘}}=

$3/2$
$2/3$
2
1

Solution:

Concept:

Use complementary angle identities:

\sin(90^\circ - \theta) = \cos \theta

and

\tan(90^\circ - \theta) = \cot \theta

.

Explanation:

Rewrite each term using the complementary angle formulas.

\frac{\sin 18^\circ}{\cos 72^\circ} = \frac{\sin(90^\circ - 72^\circ)}{\cos 72^\circ} = \frac{\cos 72^\circ}{\cos 72^\circ} = 1

.

\frac{\tan 26^\circ}{\cot 64^\circ} = \frac{\tan(90^\circ - 64^\circ)}{\cot 64^\circ} = \frac{\cot 64^\circ}{\cot 64^\circ} = 1

.

Therefore, the sum is

1 + 1 = 2

.

Answer:

2

(Option C)

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