Question 19: Find the values of cos¯¹ (cos7π/6) is equal to (A) 7π/6 (B) 5π/6 (C) π/3 (D) π/6
Class 12 - Math - Inverse Trigonometric Functions
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A) 7π/6.
There are two ways to do this.
Cos⁻¹ (Cos 7π/6) = 7π/6 Directly...
But the PRINCIPAL range of arcCos function is only [0, π].
So this is not valid...
find Cos 7π/6 value first. It is = - Sin π/6 = -1/2.
Now Cos⁻¹ (-1/2) = 5 π / 6 in the principal range [0, π].
There are two ways to do this.
Cos⁻¹ (Cos 7π/6) = 7π/6 Directly...
But the PRINCIPAL range of arcCos function is only [0, π].
So this is not valid...
find Cos 7π/6 value first. It is = - Sin π/6 = -1/2.
Now Cos⁻¹ (-1/2) = 5 π / 6 in the principal range [0, π].
kvnmurty:
:-)
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