CalcaTools

Sin Cos Converter

Converts sin cos using sin²θ + cos²θ = 1, right in your browser.

Last updated: June 2026 · Free · No sign-up required

Results

Enter values above and click Calculate to see your result instantly.

Inside the Sin Cos Converter

Behind the inputs above sits one rule: sin²θ + cos²θ = 1; tanθ = sinθ ÷ cosθ; rad = deg × π/180. The tool evaluates it instantly with the values you enter.

Scroll past the converter for a quick-reference table, a step-by-step methodology with a fully worked example, and answers to the questions people most often ask about sin cos calculator.

Quick reference

Anglesincostan
010
30°0.50.86600.5774
45°0.70710.70711
60°0.86600.51.7321
90°10undefined

functions Shows the working, not just the answer

For students and teachers, the final number is only half the value. Every math tool here exposes the formula it applied, the intermediate steps, and the rounding rule, so you can follow along, check your homework, or use the answer in a proof or report with confidence.

calculate Accurate to the spec

Calculations use 64-bit floating point with sensible rounding for the domain (currency to 2 decimals, percentages to 4 decimals, algebra to 6 significant figures). Where exact rational arithmetic matters — fractions, factorials, simplification — we use a dedicated BigNumber path so 1/3 + 1/6 returns ½, not 0.49999.

school Free for classroom use

Educators are welcome to link to any math calculator on CalcaTools from a class site, Google Classroom, or worksheet. The pages are mobile-friendly, free, ad-supported (so we can keep them free) and have no sign-up wall — students just click and use them in class or at home.

tips_and_updates Pair with the spoke articles

Below the calculator we link a small set of plain-English explainer pages — "What is a percentage?", "Why does PEMDAS matter?", and so on. They cover the underlying concept in 4–6 short paragraphs. Read those before the calculator if the topic is new, or after if you want the extra context.

Interpretation guide

QuadrantSigns (sin / cos / tan)
0–90°+ / + / +
90–180°+ / − / −
180–270°− / − / +
270–360°− / + / −

Formula & methodology

Formula: sin²θ + cos²θ = 1; tanθ = sinθ ÷ cosθ; rad = deg × π/180

  1. Enter the angle and choose degrees or radians.
  2. Degrees convert to radians (× π/180) internally.
  3. sin, cos, and tan are evaluated together.
  4. tan shows “undefined” at 90°, 270°… where cos = 0.

Example: 30° = 0.5236 rad → sin = 0.5, cos = 0.8660, tan = 0.5774.

Frequently asked questions

What are sin and cos of 30 degrees?
sin 30° = 0.5 exactly; cos 30° = √3/2 ≈ 0.8660.
How are sine and cosine related?
cos θ = sin(90° − θ) — they are the same wave shifted a quarter turn, and sin² + cos² = 1 always.
Why is tan 90° undefined?
tan = sin/cos, and cos 90° = 0 — division by zero. The tangent grows without bound as you approach 90°.
How do I convert degrees to radians?
Multiply by π/180: 30° = 0.5236 rad. Radians are the natural unit — arc length over radius.
Which common angles have exact values?
0°, 30°, 45°, 60°, 90°: sines are 0, 1/2, √2/2, √3/2, 1 — the pattern √(n)/2 for n = 0–4.

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