That tool is called a protractor.
The sextant.
A protractor.
To determine if the angle is < or> than 90 degrees so proper scale can be used
This depends on what you are measuring. A tool that can be used is a tape measure.
protractor
That tool is called a protractor.
Degrees
An angle ruler is a tool used to measuring angles like a protractor. An angle ruler is more accurate than a protractor.
Scoliometer-- A tool for measuring trunk asymmetry; it includes a bubble level and angle measure.
The sextant.
By measuring it using a suitable tool such as a ruler or caliper
A protractor.
To determine if the angle is < or> than 90 degrees so proper scale can be used
Protractor
An angle measuring more than 90 degrees is obtuse. An angle measuring less than 90 degrees is acute. An angle measuring 90 degrees is right.
The value of the relief (and rake) angle effects how the tool cuts into a particular material and the type or size of chip produced. For short: relief angle determines how deep and how rough the tool bites.