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Introduction to quadrant rule (CAST)
1st quadrant (0˚ to 90˚) → ALL trigonometric ratios are +ve
2nd quadrant (90˚ to 180˚) → Only Sine of the angle is +ve
3rd quadrant (180˚ to 270˚) → Only Tangent of the angle is +ve
4th quadrant (270˚ to 360˚) → Only Cosine of the angle is +ve
This quadrant rule can be remembered as CAST. Quadrant rule is a very useful and essential method used in solving trigonometric equations to find angles within a given range. Do learn and remember it well.
2nd quadrant (90˚ to 180˚) → Only Sine of the angle is +ve
3rd quadrant (180˚ to 270˚) → Only Tangent of the angle is +ve
4th quadrant (270˚ to 360˚) → Only Cosine of the angle is +ve
This quadrant rule can be remembered as CAST. Quadrant rule is a very useful and essential method used in solving trigonometric equations to find angles within a given range. Do learn and remember it well.