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Find the value of: 4⁢(sin2⁡30°+cos2⁡60°) −3⁢(cos2⁡45°−12 sin2⁡90°) - Mathematics

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प्रश्न

Find the value of:

`4 (sin^2 30° + cos^2 60°) − 3 (cos^2 45° − 1/2  sin^2 90°)`

बेरीज
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उत्तर

Given:

`4 (sin^2 30° + cos^2 60°) − 3 (cos^2 45° − 1/2  sin^2 90°)`

Step 1: Use standard trigonometric values

sin 30° = `1/2 → sin^2 30° = 1/4`

cos 60° = `1/2 → cos^2 60° = 1/4`

cos 45° = `1/sqrt2 → cos^2 45° = 1/2`

sin 90° = 1 → `sin^2 90° = 1`

Step 2: Substitute the values

`4(1/4 + 1/4) = 4 ⋅ 2/4 = 4 ⋅ 1/2 = 2`

`3(1/2 − 1/2 ⋅ 1) = 3 (1/2 − 1/2) = 3(0) = 0`

= 2 − 0   ...[Subtracting]

= 2

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पाठ 19: Trigonometry - EXERCISE 19C [पृष्ठ २३६]

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बी निर्मला शास्त्री Mathematics [English] Class 9 ICSE
पाठ 19 Trigonometry
EXERCISE 19C | Q I. 3. | पृष्ठ २३६
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