Trigonometry
Compute all six trigonometric functions (sin, cos, tan, csc, sec, cot) for any angle. Quadrant, reference angle, Pythagorean identity check. Overview of trigonometry.
Examples — Click to Load
All 6 Trig Functions
Function Values
sin² vs cos² (Pythagorean)
Calculation Breakdown
⚠️For educational and informational purposes only. Verify with a qualified professional.
Key Takeaways
- • sin θ = opposite/hypotenuse, cos θ = adjacent/hypotenuse in a right triangle
- • tan = sin/cos, cot = cos/sin, sec = 1/cos, csc = 1/sin
- • Quadrant I: all +; II: sin,csc +; III: tan,cot +; IV: cos,sec + (ASTC)
- • sin²θ + cos²θ = 1 always (Pythagorean identity)
- • On the unit circle: (cos θ, sin θ) is the point at angle θ
Did You Know?
How It Works
Right Triangle Definition
In a right triangle with angle θ: sin θ = opposite/hypotenuse, cos θ = adjacent/hypotenuse, tan θ = opposite/adjacent. SOH-CAH-TOA.
Unit Circle Definition
For any angle θ, the point on the unit circle is (cos θ, sin θ). This extends trig to all angles. tan = y/x, sec = 1/x, csc = 1/y, cot = x/y. See Unit Circle Calculator.
Quadrant Signs
All positive in Q1. In Q2: sin,csc +. In Q3: tan,cot +. In Q4: cos,sec +. Use the reference angle and apply the sign from the quadrant.
Expert Tips
Memorize Special Angles
30°, 45°, 60°: sin = √1/2, √2/2, √3/2. cos is reversed. Use Unit Circle.
Reciprocal Functions
csc = 1/sin, sec = 1/cos, cot = 1/tan. When sin or cos = 0, the reciprocal is undefined.
Degrees vs Radians
360° = 2π rad. Calculus uses radians: d/dx[sin(x)] = cos(x) only when x is in radians.
Pythagorean Identity
sin²θ + cos²θ = 1 always. Use it to find one from the other. See Trig Identities.
Trig Calculator vs Other Tools
| Feature | This Calculator | Scientific Calc | Manual |
|---|---|---|---|
| All 6 functions at once | ✅ | ❌ One at a time | ❌ |
| Quadrant & reference | ✅ | ❌ | ✅ Slow |
| Visual charts | ✅ | ❌ | ❌ |
| Step-by-step | ✅ | ❌ | ✅ |
| Pythagorean check | ✅ | ❌ | ⚠️ Manual |
| Copy & share | ✅ | ❌ | ❌ |
| Degrees & radians | ✅ | ✅ | ✅ |
| Examples | ✅ | ❌ | ❌ |
Frequently Asked Questions
What are the six trig functions?
Sine (sin), cosine (cos), tangent (tan), cosecant (csc = 1/sin), secant (sec = 1/cos), cotangent (cot = 1/tan). The first three are primary; the others are reciprocals.
When is tan undefined?
When cos θ = 0, i.e., at 90° and 270°. At those angles, the point on the unit circle has x = 0, so tan = y/x is undefined.
What is the range of sin and cos?
Both have range [-1, 1]. Tan, cot, sec, and csc can be any real number or undefined.
How do I find trig values without a calculator?
Memorize 30°, 45°, 60°, 90°. Use reference angles for other angles. Apply quadrant signs. sin(30°)=1/2, sin(45°)=√2/2, sin(60°)=√3/2.
What is the period of sin and cos?
360° or 2π radians. sin(θ + 360°) = sin(θ). For tan and cot, the period is 180° or π.
Why are radians used in calculus?
Derivatives are simpler: d/dx[sin(x)] = cos(x) when x is in radians. In degrees, you need an extra factor of π/180.
What is the Pythagorean identity?
sin²θ + cos²θ = 1 for every angle. It comes from x² + y² = 1 on the unit circle. Used to derive many other identities.
Where is trigonometry used?
Physics (waves, forces), engineering (structures, signals), computer graphics (rotations), music (sound waves), navigation, astronomy, and more.
Trigonometry by the Numbers
Official & Educational Sources
Disclaimer: Results for educational use. Uses standard IEEE 754 floating-point. Verify for mission-critical applications.
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