Alright, lets get started.
tan Ф = -21
Using inverse function,
Ф = [tex] tan^{-1} (-21) [/tex]
Using calculator, we could find ta inverse value
Ф = - 87.3°
But as per given question, angle must lie between 0 and 180 degrees.
Means angle should present in first or second quadrant.
As tan value is given negative (-21), means angle will be in second quadrant.
If we add 180 degrees in our angle, the angle will lie in second quadrant. (refer the diagram)
Ф = - 87.27 + 180 = 92.73°
Ф = 92.73° : Answer
Hope it will help :)
