Half Angle Calculator
Calculate sin(θ/2), cos(θ/2), tan(θ/2) using half-angle formulas with quadrant analysis.
Input
Quick Values:
Half Angle (θ/2 = 30.00°) - Quadrant 1
sin(θ/2) = 0.50000000
cos(θ/2) = 0.86602540
tan(θ/2) = 0.57735027
Both Possible Values (±)
sin(θ/2) = ±√((1-cosθ)/2)
+0.500000 or -0.500000
cos(θ/2) = ±√((1+cosθ)/2)
+0.866025 or -0.866025
cos(θ) used in formulas:
0.50000000
Half Angle Formulas
sin(θ/2)
= ±√((1 - cos(θ))/2)
cos(θ/2)
= ±√((1 + cos(θ))/2)
tan(θ/2)
= sin(θ)/(1 + cos(θ))
= (1 - cos(θ))/sin(θ)
Note: The sign (+ or -) depends on which quadrant θ/2 lies in.
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
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Formula Source: Handbook of Mathematical Functions
by Abramowitz & Stegun
🔄Last reviewed: May 2026
✓Formula checks are based on standard references and internal QA review.