Cos 770-sin 20-cos 59-sin 31-8 sin 2 30-

The correct option is B 0 cos70^∘/sin20^∘+cos59^∘/sin31^∘ 8 sin^2 30^∘ =sin20^∘/sin20^∘ + nbsp;sin31^∘/sin31^∘ 8(1/2)^2 (∵ cosθ = sin(90^∘ θ), sin30^∘ = ...

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Byju's Answer

Standard IX

Mathematics

Trigonometric Ratios of Standard Angles

cos 770∘/sin ...

Question

$\frac{c o s 70^{\circ}}{s i n 20^{\circ}} + \frac{c o s 59^{\circ}}{s i n 31^{\circ}} - 8 s i n^{2} 30^{\circ} =$

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Solution

The correct option is C
0

$\frac{c o s 70^{\circ}}{s i n 20^{\circ}} + \frac{c o s 59^{\circ}}{s i n 31^{\circ}} - 8 s i n^{2} 30^{\circ}$

$= \frac{s i n 20^{\circ}}{s i n 20^{\circ}} + \frac{s i n 31^{\circ}}{s i n 31^{\circ}} - 8 (\frac{1}{2})^{2}$

$(∵ c o s θ = s i n (90^{\circ} - θ), s i n 30^{\circ} = \frac{1}{2})$

$= 1 + 1 - 8 \times \frac{1}{4}$
$= 2 - 2 = 0$

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Similar questions

Q. Find:

\frac{c o s 70^{\circ}}{s i n 20^{\circ}} + \frac{c o s 59^{\circ}}{s i n 31^{\circ}} - 8 s i n^{2} 30^{\circ} =

______.

Q. Evaluate

\frac{c o s 70^{\circ}}{s i n 20^{\circ}} + \frac{c o s 59^{\circ}}{s i n 31^{\circ}} - 8 s i n^{2} 30^{\circ} = 0

\frac{c o s 70^{\circ}}{s i n 20^{\circ}} + \frac{c o s 59^{\circ}}{s i n 31^{\circ}} - 8 s i n^{2} 30^{\circ}

is equal to

Q. Find the value of the following expression.

\frac{c o s 70^{\circ}}{s i n 20^{\circ}} + \frac{c o s 59^{\circ}}{s i n 31^{\circ}} - 8 s i n^{2} 30^{\circ}

Q. Find the value of:

\frac{cos 70^{\circ}}{sin 20^{\circ}} + \frac{cos 59^{\circ}}{sin 31^{\circ}} + \frac{cos θ}{sin (90 - θ)} - 8 {cos}^{2} 60^{\circ}

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cos70∘sin20∘+cos59∘sin31∘−8sin230∘=

The correct option is C 0 cos70∘sin20∘+cos59∘sin31∘−8sin230∘ =sin20∘sin20∘+sin31∘sin31∘−8(12)2 (∵ cosθ=sin(90∘−θ), sin30∘=12) =1+1−8×14 =2−2=0

$\frac{c o s 70^{\circ}}{s i n 20^{\circ}} + \frac{c o s 59^{\circ}}{s i n 31^{\circ}} - 8 s i n^{2} 30^{\circ} =$