Question

cos230° cos²45°+ 4sec²60°+1/2cos²90°- 2tan²60°​

Answer 1

Answer:

cos² 30° + cos² 45° + cos² 60° + cos² 90°            

= (√3/2)² + (1/√2)² + (½)²  + 0

= ¾ + ½ + ¼ + 0

= ¾ + ¼ + ½ + 0

= (3 + 1) /4 + ½

[ By taking L.C.M]

= 4/4 + ½

= 1 + 1/2

= (2+1)/2 = 3/2

[ By taking L.C.M]

cos² 30° + cos² 45° + cos² 60° + cos² 90° = 3/2

[cos 30° = √3/2   , cos 45° =1/√2 , cos 60° = 1/2 ,  cos 90° = 0]

Hence, cos² 30° + cos² 45° + cos² 60° + cos² 90° = 3/2.

Step-by-step explanation:

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Answer 2

The correct answer is 83/8

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