Sum of all angles on a straight line is ______.
180 degrees
90 degrees
200 degrees
100 degrees
In order to construct a 90∘ angle, we draw a straight line first. The angle measure of a straight line is ___ (in degrees).
The sum of a pair of opposite angles of a cyclic quadrilateral is 180 degrees .
The angle formed on a straight line is ___ (in degrees).