Acute Triangle

Since all angles are acute, or less than 90 degrees, an equilateral triangle is also an acute triangle. Lesson Summary An acute triangle is a triangle in which all three angles measure less than 90 degrees.

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Equilateral Triangle

In geometry, an equilateral triangle is a triangle in which all three sides are equal. In the familiar Euclidean geometry, equilateral triangles are also equiangular; that is, all three internal angles are also congruent to each other and are each 60°.

Isosceles Trapezium

In Euclidean geometry, an isosceles trapezoid (isosceles trapezium in British English) is a convex quadrilateral with a line of symmetry bisecting one pair of opposite sides. It is a special case of a trapezoid.

Isosceles Triangle

A triangle has three sides and three angles : The three angles always add to 180° Equilateral, Isosceles and Scalene. There are three special names given to triangles that tell how many sides (or angles) are equal. There can be 3, 2 or no equal sides/angles: Equilateral Triangle . Three equal sides Three equal angles, always 60° Isosceles Triangle . Two equal sides Two equal angles Scalene ...

Kite

In Euclidean geometry, a kite is a quadrilateral whose four sides can be grouped into two pairs of equal-length sides that are adjacent to each other. In contrast, a parallelogram also has two pairs of equal-length sides, but they are opposite to each other rather than adjacent.

Obtuse Triangle

Obtuse Triangle. more ... A triangle that has an angle greater than 90 ...

Rectangle

Is a Square a type of Rectangle? (Yes) Is a Rectangle a type of Kite? (No) Complex Quadrilaterals. Oh Yes! when two sides cross over, we call it a "Complex" or "Self-Intersecting" quadrilateral, like these: They still have 4 sides, but two sides cross over. Polygon. A quadrilateral is a polygon.

Rectangle Opposite Sides are Parallel and Equal

A square has equal sides and every angle is a right angle (90°) Also opposite sides are parallel. A square also fits the definition of a rectangle (all angles are 90°), and a rhombus (all sides are equal length). The Parallelogram. A parallelogram has opposite sides parallel and equal in length.

Rhombus

A square has equal sides and every angle is a right angle (90°) Also opposite sides are parallel. A square also fits the definition of a rectangle (all angles are 90°), and a rhombus (all sides are equal length). The Parallelogram. A parallelogram has opposite sides parallel and equal in length.

Scalene Triangle

Scalene Triangle . No equal sides No equal angles ... Interactive Triangles Right Angled triangles Proof that a Triangle has 180° Pythagoras' Theorem Geometry Index.

Square

Is a Square a type of Rectangle? (Yes) Is a Rectangle a type of Kite? (No) Complex Quadrilaterals. Oh Yes! when two sides cross over, we call it a "Complex" or "Self-Intersecting" quadrilateral, like these: They still have 4 sides, but two sides cross over. Polygon. A quadrilateral is a polygon.

Trapezium

Quadrilaterals. Quadrilateral just means "four sides" (quad means four, lateral means side). A Quadrilateral has four-sides, it is 2-dimensional (a flat shape), closed (the lines join up), and has straight sides.