1 - 2 c o s 60 o - c o s 80 o 2 s i n 10 o = ….

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Question: Answered & Verified by Expert

\frac{1 - 2 [c o s 60^{o} - c o s 80^{o}]}{2 s i n 10^{o}} =

….

MathematicsTrigonometric Ratios & IdentitiesMHT CETMHT CET 2019 (Shift 1)

Options:

A 2
B 1
C $\frac{1}{2}$
D $\frac{3}{2}$

Solution:

2517 Upvotes Verified Answer

The correct answer is: 1

We have,

\frac{1 - 2 (c o s 60^{o} - c o s 80^{o})}{2 s i n 10^{o}}

= \frac{1 - 2 (\frac{1}{2} - c o s 80^{o})}{2 s i n 10^{o}}

= \frac{2 c o s 80^{o}}{2 s i n 10^{o}}

= \frac{\cos (90^{o} - 10^{o})}{s i n 10^{o}}

= \frac{s i n 10^{o}}{s i n 10^{o}} = 1

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