Q30 of 186 Page 350

cos2 30° cos2 45° + 4 sec2 60° + 2cos2 90° – 2 tan2 60° = ?

Consider cos2 30° cos2 45° + 4 sec2 60° + 2cos2 90° – 2 tan2 60°

= 3 (1/2)2 + 2(√3)2 – 5(1/√2)2


= 3(1/4) + 2(3) – 5(1/2)


= (3/4) + 6 – (5/2)


= (3 + 24 – 10)/4


= 17/4

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