
It is the only triangle that has angles in the proportion 1:1:2 and has angles of 36°, 72°, and 72°. The golden triangle is an acute isosceles triangle where the ratio of twice the the side to the base side is the golden ratio.The Morley triangle is a special equilateral (and thus acute) triangle that is formed from any triangle where the vertices are the intersections of the adjacent angle trisectors.

If C is the greatest angle and h c is the altitude from vertex C, then the following relation for altitude is true for an acute triangle:įor an acute tirangle with angles A, B, and C: In an acute triangle, the following is true for the length of the sides:Ī 2 + b 2 > c 2, b 2 + c 2 > a 2, c 2 + a 2 > b 2

An obtuse triangle may be either isosceles (two equal sides and two equal angles) or scalene (no equal sides or angles).The longest side of an obtuse triangle is the one opposite the obtuse angle vertex.It's impossible for a triangle to have more than one obtuse angle. Because all the angles in a triangle add up to 180°, the other two angles have to be acute (less than 90°). None of its sides are equal in length.Ivan De Sousa/EyeEm/Getty Images Obtuse Triangle DefinitionĪn obtuse triangle is one that has an angle greater than 90°. The perpendicular bisector of creates two smaller isosceles triangles. ObtuseĪn obtuse triangle has three different angles, with one angle greater than 90°. What is true about triangle XYZ Select three options. ScaleneĪ scalene triangle has three different angles and none of its sides are equal in length. In this case the angles would be 90°, 45° and 45°. It is possible for a triangle to be a right-angled triangle and an isosceles triangle at the same time. That 90° angle is shown as a small square where two sides of the triangle join. Right-angled triangleĪ right-angled triangle has one 90° angle. It is easy to work out the missing angles of an isosceles triangle by looking for the angles that should be equal. It can be drawn to have two equal sides and two equal angles or with two acute angles and one obtuse angle. IsoscelesĪn isosceles triangle can be drawn in many different ways. It will always have angles of 60° in each corner. EquilateralĪn equilateral triangle has three equal sides and angles. On a diagram, equal sides of a triangle have one small line or dash drawn on each side. The sum of angles in any triangle is 180°.

What are the different types of triangle?
