# How to build a obtuse triangle with a compass and a ruler

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Butterfly

Answered 19 march 2017 23:41

The compass, apparently, is needed to determine an obtuse angle, although a triangle can be drawn without it. A blunt angle is an angle larger than a right angle (90 degrees). Right angle is 1/4 of a circle. To draw an obtuse triangle, draw a weak circle first, then draw a thin line along the radius from above and across, you will get a division into four equal sectors, each will be 90 degrees. One of these four lines can be one side of a triangle, and the other one outside the sector, also from a radius. So you get two sides of an obtuse triangle with one vertex. Connect them and you will have a triangle. The circumference as an auxiliary element can be erased.