1.

The value of 4 cot2 45° – sec260º + sin2 60° + cos2 90° is(a) \(\frac12\)(b) \(\frac34\) (c) 1 (d) \(\frac{11}{16}\)

Answer»

(b) \(\frac34\)

4 cot2 45° – sec2 60° + sin2 60° + cos2 90° 

= 4 (cot 45°)2 – (sec 60°)2 + (sin 60°)2 + (cos 90°)2

= 4 × 12 – (2)2\(\bigg(\frac{\sqrt3}{2}\bigg)\) + (0)2

= 4 - 4 + \(\frac34\) + 0 = \(\frac34\).



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