# Need math help with a Heptagon

**Question description**

Given a Heptagon inscribed inside a unit circle, what algebraic formula may be used to approximate the coordinates of each point of the Heptagon?

According to "Trigonometry for Dummies (p. 147)," one may use an infinite series to approximate sine and cosine of angles around the unit circle. Although, it mentions the infinite series is only accurate from 90 to -90 degrees. Why is this?

```
The infinite series for sine is: sin(x) = x - x^3/3! + x^5/5! - x^7/7!... 'x' must be in radians, not degrees.
```

The infinite series for cos(x) = 1 - x^2/2! + x^4/4! - x^6/6! + x^8/8!... 'x' must be in radians, not degrees.

If it is true that an infinite series is only accurate from 90 to -90 degrees, what formula accurately approximates the coordinates of each point of the Heptagon?

Below is my attempt at using the infinite series in the "Trigonometry for Dummies" book. It just doesen't seem like the values are correct.

heptagon.pdf## Tutor Answer

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