Question

Which of the following equations have solutions ?
1) cos 20 = -1 b) cos2 0 = 1 c) 2 sin 0 = 3 d) 3 tan 0 = 5​

Answer 1

Answer:

None of the equation is correct.

a) Cos 20° = -1

The angle 20°  lies in 1st quadrant and has all the trignometric ratios positive.

So, equation 1 is disproved.

b) Cos 20° = 1

Cosine in first quadrant can only become 1 when the angle is zero, i.e., Cos 0°  = 1

c,d) Sine 0°  and Tan 0° both are 0;