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Sine and Cosine Values of Special Angles

Main definitions and formulas:

• A 45-45-90 triangle has side lengths in proportion to 1-1-√ 2.
• A 30-60-90 triangle has side lengths in proportion to 1-√ 3-2.

• Degrees Radians Cosine Sine 0 0 1 0 30 π 6 √ 3 2 1 2 45 π 4 √ 2 2 √ 2 2 60 π 3 1 2 √ 3 2 90 π 2 0 1

• Use these values to find sines and cosines in other quadrants. The mnemonic ASTC (All Students Take Calculus) helps you remember which ones are positive in which quadrant. (All, Sine, Tangent, Cosine)