Angles are measured either in degrees or in radians.
Measure an angle!
60'
By using trigonometry
There is no reason why an angle cannot have any value.
Into minutes, then seconds. A 1 degree angle is 60", 0' or, a 1 degree angle can be expressed as 0", 3600' a .5 degree angle can be expressed as 30", and so on.
Unless you are ready for some complicated trigonometry, I would suggest that you use a protractor and draw a 50 degree angle BEYOND a right angle.
The angle of reference is in the first quadrant, and 90 degrees angle is not in the quadrant.
plane trigonometry spherical trigonometry
The main kinds are plane trigonometry and solid trigonometry. The latter will include trigonometry in hyper-spaces.
Hipparchus is the father of trigonometry.
It is a number - in trigonometry or elsewhere.
TRIGONOMETRY