Question

find the principal value of
cos inverse (-1/2)

Answer 1

Hope you got the required answer

Answer 2

Answer:

Cos ( 2π/3 )

Step-by-step explanation:

Range = ( 0, 180 ) = ( 0, π )

We know that Cos function is negative only in 2 quadrant in its range.

Hence, let us assume A = Cos⁻¹ ( -1/2 )

⇒ Cos A = -1/2

We know that, Cos 60 is only 1/2 in first quadrant. Hence in second quadrant it would be ( 180 - 60 ), which is 120°

120 is 2π/3.

Hence Principal Value of Cos⁻¹ ( -1/2 ) is ( 2π/3 ).

Hope it helped !!