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Contents
Ratio for Negative Angles
Ratio for Complementary Angles
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Negative Angles The rotating arm will describe a negative angle if it rotates in a clockwise direction. To convert a negative angle to a normal, add 360° or a multiple of 360°. The value of any negative angle can be found.
Example
sin(-40°) = sin 320° = -sin (360° - 320°) = -sin 40° cos(-40°) = cos 320° = cos (360° - 320°) = cos 40° tan(-40°) = tan 320° = -tan (360° - 320°) = -tan 40°
Hence, in general, sin (-q ) = -sin q cos(-q ) = cos q tan(-q ) = -tan q and these will be true for any negative angles
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Express the trigonometric ratios of -40° in terms of its basic angles.
basic angle is in 4th quadrant
