Trig. Equations Examples using CAST Diagrams
More Lessons for A Level Maths
Videos, activities and worksheets that are suitable for A Level Maths.
What is the CAST diagram?
The Cast diagram helps us to remember the signs of the trigonometric functions in each of the quadrants.
The CAST diagram is also called the Quadrant Rule or the ASTC diagram.
In the first quadrant, the values are all positive.
In the second quadrant, only the values for sin are positive.
In the third quadrant, only the values for tan are positive.
In the fourth quadrant, only the values for cos are positive.
Note that the mnemonic CAST goes anticlockwise starting from the 4th quadrant.
Quadrant Rule or CAST diagram
Using the Quadrant Rule to solve trig. equations
Quadrant Rule for solving trig equations with different ranges
Core (2) Graphs of Trigonometric Functions (4) - CAST Diagram or Unit Circle
Rotate to landscape screen format on a mobile phone or small tablet to use the Mathway widget, a free math problem solver that answers your questions with step-by-step explanations.
You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.