1.

The solution of the equation cos2 x + sin x + 1 = 0 lies in the interval A. (- \(\frac{π}4\),\(\frac{π}4\) ) B. (- \(\frac{π}3\), \(\frac{π}4\)) C. (\(\frac{3π}4\), \(\frac{5π}4\)) D. (\(\frac{5π}4\), \(\frac{7π}4\))

Answer»

1 - sin2x + sin x+1 = 0 

sin2x - sin x - 2 = 0 

sin x = -1 

so, x= \(\frac{3π}2\)

and it lies between (\(\frac{5π}4\), \(\frac{7π}4\)

Option D



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