Cosine Calculator

Cosine – Quick Cheat Sheet

• Definition: \(\cos(\theta)\) is the x-coordinate on the unit circle at angle \(\theta\) (radians).
• Degrees → Radians: \(\theta_{\text{rad}} = \theta_{\text{deg}} \times \pi/180\).
• Range: \([-1, 1]\).   Period: \(2\pi\).   Even: \(\cos(-\theta)=\cos(\theta)\).
• Common values (degrees): 0°→1, 30°→√3/2, 45°→√2/2, 60°→1/2, 90°→0, 120°→−1/2, 135°→−√2/2, 150°→−√3/2, 180°→−1.
• Identities: \(\cos^2\theta+\sin^2\theta=1\),   \(\cos(\alpha\pm\beta)=\cos\alpha\cos\beta\mp\sin\alpha\sin\beta\).
• Precision: Increasing decimal places only changes display—internal math uses double precision.