1. Evaluate sin15° cos15° - cos15° - cos75° sin75° 2. Evaluate cot54° ÷ tan36° + tan20° ÷ cot70° - 2 3. Express the following in terms of angle between 0 °and 45° -- cosec 68° + cot72° 4. Evaluate cot²41° ÷ tan²49° - 2sin²75° ÷ cos²15°
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Answer:
(1)sin 15 .cos(90-15) - cos(90-75) .sin 75
=sin 15.sin75 - sin 15 .sin 75
=0
(2)tan(90-x) = cot(x)
so cot 54 /tan 36 = cot54/ cot 54 =1
||ly for tan20/cot70 = 1
so 1+1-2=0
(3)cosec 68 + cot 75
=cosec (90-22)+cot(90-18)
=sec 22 + ten 18
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