---
id: 5900f43e1000cf542c50ff50
challengeType: 5
title: 'Problem 210: Obtuse Angled Triangles'
forumTopicId: 301852
---

## Description
<section id='description'>
Consider the set S(r) of points (x,y) with integer coordinates satisfying |x| + |y| ≤ r.
Let O be the point (0,0) and C the point (r/4,r/4).
Let N(r) be the number of points B in S(r), so that the triangle OBC has an obtuse angle, i.e. the largest angle α satisfies 90°<α<180°.
So, for example, N(4)=24 and N(8)=100.

What is N(1,000,000,000)?
</section>

## Instructions
<section id='instructions'>

</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: <code>euler210()</code> should return 1598174770174689500.
    testString: assert.strictEqual(euler210(), 1598174770174689500);

```

</section>

## Challenge Seed
<section id='challengeSeed'>

<div id='js-seed'>

```js
function euler210() {
  // Good luck!
  return true;
}

euler210();
```

</div>



</section>

## Solution
<section id='solution'>

```js
// solution required
```

</section>