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If xtan60° + cos45° = sec45°, then the value of x2 + 1 is?

A. $$\frac{6}{7}$$

B. $$\frac{7}{6}$$

C. $$\frac{5}{6}$$

D. $$\frac{6}{5}$$

Answer: Option B

Solution(By Examveda Team)

$$\eqalign{ & \Rightarrow x\tan {60^ \circ } + \cos {45^ \circ } = \sec {45^ \circ } \cr & \Rightarrow x.\sqrt 3 + \frac{1}{{\sqrt 2 }} = \sqrt 2 \cr & \Rightarrow x\sqrt 6 + 1 = 2 \cr & \Rightarrow x = \frac{1}{{\sqrt 6 }} \cr }$$
Squaring both sides and addition 1 both sides
$$\eqalign{ & \Rightarrow {x^2} + 1 = {\left( {\frac{1}{{\sqrt 6 }}} \right)^2} + 1 \cr & \Rightarrow {x^2} + 1 = \frac{1}{6} + 1 \cr & \Rightarrow {x^2} + 1 = \frac{7}{6} \cr} $$

This Question Belongs to Arithmetic Ability >> Trigonometry

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