This is the seventh tutorial of the GeoGebra Intermediate Tutorial Series. If this is your first time to use GeoGebra, please read the GeoGebra Essentials Series. In the Graphs and Sliders posts (click here and here ), we have discussed how to use number sliders. In this tutorial, we use the Angle slider to rotate a triangle in […]

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# Posts tagged with 'angle sum of a triangle'

## Why is the angle sum of the interior angles of a triangle 180 degrees?

We were taught that the sum of the measures of interior angles of a triangle is 180 degrees. But how come? Is it true no matter what the shape or size of the triangle? Recall that an angle is the amount of rotation of a ray. In Figure 2, the ray was rotated from A […]

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## Sum of the interior angles of a polygon

We were taught that if we let be the angle sum (the total measure of the interior angles) and be the number of vertices (corners) of a polygon, then . For example, a quadrilateral has vertices, so its angle sum is degrees. Similarly, the angle sum of a hexagon (a polygon with sides) is degrees. […]

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