ForHosting KIT · Developer Utilities

Tangent circle calculator

A tangent to a circle is a straight line that meets the circumference at exactly one point.

● BetaFree · in your browser

Use it from WebAPIEmailTelegramApp soon

When that line is drawn from a point that sits outside the circle, the useful number is not the infinite line but the finite segment from the external point to the contact point. That segment length is completely determined by two measurements you already have in most textbook and CAD problems: the circle radius and the distance from the center to the given point. This tangent-circle calculator applies the right-triangle identity that follows from the radius being perpendicular to the tangent at the point of contact. The tangent length equals the square root of the center distance squared minus the radius squared. Interior points are rejected because no real tangent exists when the distance is less than the radius. The same deterministic module powers the free browser widget and the API, so classroom checks and automation scripts always agree on the length and on the error case.

How to use it

Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.

Check your inputs

Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.

Use it again or automate it

Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.

What you can do with it

Get an answer now

Enter one set of values and see the result without building a spreadsheet or script.

Compare scenarios

Change one value at a time and rerun the calculation to understand what affects the result.

Automate repeated work

Use the API when the same calculation needs to run inside your product or workflow.

FAQ

How do I use this capability?

Complete the fields above and run it on this page. The form highlights anything that needs attention.

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/math/tangent-circle

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/math/tangent-circle \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"radius":3,"distance":5}'

const res = await fetch("https://api.kit.forhosting.com/math/tangent-circle", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "radius": 3,
    "distance": 5
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/math/tangent-circle",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "radius": 3,
    "distance": 5
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/math/tangent-circle", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"radius":3,"distance":5}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"radius":3,"distance":5}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/math/tangent-circle", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "radius": 3,
  "distance": 5
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "math.tangent_circle",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Read the full KIT documentation →