Noun
straight angle (plural straight angles)
(mathematics, geometry) An angle that is equal to 180° (pi radians or two right angles).
Adjacent angles which sum to a right angle, straight angle or full angle are special and are respectively called complementary, supplementary and explementary angles (see "Combine angle pairs" below). Source: Internet
Supplementary angles are formed when a ray shares the same vertex and is pointed in a direction that is in between the two original rays that form the straight angle (180 degree angle). Source: Internet
The racquet movement is typically used to suggest a straight angle but then play the stroke cross court, or vice versa. Source: Internet