The value of cot ⁡ 70 o + 4 cos ⁡ 70 o is

Question

The value of cot ⁡ 70 o + 4 cos ⁡ 70 o is, 1, 2, 3, 4

MARKS App · Accepted Answer

cot ⁡ 70 o + 4 cos ⁡ 70 o = cos ⁡ 70 ° + 4 cos ⁡ 70 o sin ⁡ 70 o sin ⁡ 70 o = sin ⁡ 20 ° + 2 × 2 sin ⁡ 20 ° cos ⁡ 20 ° cos ⁡ 20 ° = sin ⁡ 20 + 2 sin ⁡ 40 o cos ⁡ 20 o = ( sin ⁡ 20 + sin ⁡ 40 o ) + sin ⁡ 40 o cos ⁡ 20 o = 2 × 1 2 cos ⁡ 10 o + cos ⁡ 50 o cos ⁡ 20 o = cos ⁡ 10 o + cos ⁡ 50 o cos ⁡ 20 o = 2 cos ⁡ 30 o × cos ⁡ 20 o cos ⁡ 20 o = 2 × 3 2 = 3

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