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Find the ratio of (sin² 22° + sin² 68°) and (cos² 33° + cos² 57°).
Question

Find the ratio of (sin² 22° + sin² 68°) and (cos² 33° + cos² 57°).

A.

1:4

B.

1:1

C.

1:2

D.

2:1

Correct option is B

Given:

We need to find the ratio of

sin222+sin268andcos233+cos257.\sin^2 22^\circ + \sin^2 68^\circ and \cos^2 33^\circ + \cos^2 57^\circ .

Formula Used:

1. Use the trigonometric identity: sin2θ+cos2θ=1\sin^2 \theta + \cos^2 \theta = 1​ .
2. Use complementary angles for sine and cosine:
sin(90θ)=cosθ- \sin(90^\circ - \theta) = \cos \theta
cos(90θ)=sinθ- \cos(90^\circ - \theta) = \sin \theta


Solution:

1. Calculate sin222+sin268\sin^2 22^\circ + \sin^2 68^\circ​ :

- Using the complementary angle property, sin68=cos22\sin 68^\circ = \cos 22^\circ​ .
- Therefore, sin222+sin268=sin222+cos222\sin^2 22^\circ + \sin^2 68^\circ = \sin^2 22^\circ + \cos^2 22^\circ​ .

- Using sin2θ+cos2θ=1\sin^2 \theta + \cos^2 \theta = 1​ , we get:
sin222+sin268=1\sin^2 22^\circ + \sin^2 68^\circ = 1​ .


2. Calculate cos233+cos257\cos^2 33^\circ + \cos^2 57^\circ​ :

- Using the complementary angle property, cos57=sin33\cos 57^\circ = \sin 33^\circ​ 
- Therefore, cos233+cos257=cos233+sin233\cos^2 33^\circ + \cos^2 57^\circ = \cos^2 33^\circ + \sin^2 33^\circ​ 

- Using sin2θ+cos2θ=1\sin^2 \theta + \cos^2 \theta = 1​ , we get:
cos233+cos257=1\cos^2 33^\circ + \cos^2 57^\circ = 1​ .


3. Find the Ratio:

The ratio is sin222+sin268cos233+cos257=11=1\frac{\sin^2 22^\circ + \sin^2 68^\circ}{\cos^2 33^\circ + \cos^2 57^\circ} = \frac{1}{1} = 1​ .


Answer: The ratio is 1:1.

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