You cannot, you must use a protractor.
It is possible to construct a 20 degree angle using only Ruler and Compass. I happened to stumble across a method that is highly accurate. It is posted on my blog. Check the related link
A 10 degree angle cannot be constructed using only a compass and straight edge.
by 60 degree and 90 degree
With a straight edge and a protractor
Construct a circle and divide the circumference into 36 equal arcs Each arc will represent 10 degrees and 11 of them subtended to the circle's centre will create an obtuse angle of 110 degrees
by using a ruler and a compass
It is possible to construct a 20 degree angle using only Ruler and Compass. I happened to stumble across a method that is highly accurate. It is posted on my blog. Check the related link
A 10 degree angle cannot be constructed using only a compass and straight edge.
by 60 degree and 90 degree
Construct 2 perpendicular lines which will meet at 90 degrees then by bisecting this angle wll give a 45 degree angle
With a straight edge and a protractor
use trisection method
first draw a ray .
Most often, a construction in math is when you are asked to construct a geometric object, such as an equilateral triangle, using tools such as a compass and a ruler.
Draw a point, and a long straight line through it. Put the centre of the compass over the point, with north on the compass (or zero degrees) on the line. Then draw a second line out from the point at 80 degrees on the compass. You'll then have a 80 degree angle between the lines. It's usually a trick that teachers decide to do on their pupils. A compass is what you use to find north and a pair of compasses is used to draw circles.
Construct a circle and divide the circumference into 36 equal arcs Each arc will represent 10 degrees and 11 of them subtended to the circle's centre will create an obtuse angle of 110 degrees
With the ruler and compass construct a right angle isosceles triangle with a base of 9 cm At 4 cm from the LHS or RHS of the base draw a line that meets the apex of the triangle The angle of this line will be 40 degrees because each 1 cm of base space represents 10 degrees when joined to the apex