Cast Diagram Rules. The cast rule is a special rule used often as a memorization acronym in trigonometry. In the third quadrant only the values for tan are positive.
Cast rule of trigonometry helps us. On a set of axes angles are measured anti clockwise from the positive x axis. The cast diagram for negative cosine is as shown.
The angles which lie between 0 and 90 are said to lie in the first quadrant.
It is important to remember that these are use case diagram guidelines and not rules. Cast rule of trigonometry cast rule of trigonometry is very important to know before beginning to learn trigonometry. The cast diagram is also called the quadrant rule or the astc diagram. So 30 would be drawn as follows.
