A simple checking mechanism for any geometry problem is to estimate the length of a side or the size of an angle before you begin to calculate.

Angle (scroll down for triangles)

Estimate the angle shown. Change the slider to include angles up to 360 degrees.

Sides and Angle on a Right Angled Triangle

On this applet just one side or one angle is measured. There isn’t enough information to calculate the side/angle requested. Estimate the side by comparing it to the given side. Aim for less than 10% or 5% error!

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