Flash Cards: A Tale of Three Intersecting Lines

A triangle is a closed shape made of three sides and three vertices.

The corners of a triangle are called vertices.

An equilateral triangle is a triangle where all three sides are of equal length.

An isosceles triangle has two sides that are of equal length.

A scalene triangle has all sides of different lengths.

The sum of the lengths of any two sides of a triangle must be greater than the length of the third side.

The sum of the angles in a triangle is always 180°.

Draw a base, then draw arcs from each endpoint with the same radius equal to the side length; the intersection is the third vertex.

Circles help to determine distances equal to side lengths easily, ensuring accuracy in triangle construction.

No, because 3 + 4 is not greater than 8; it doesn't satisfy the triangle inequality.

1. Draw base AB = 4 cm. 2. Use compass from A to mark 5 cm arc. 3. Use compass from B to mark 6 cm arc. 4. Join points to form triangle.

An altitude is a perpendicular line segment from a vertex to the opposite side.

An obtuse triangle has one angle greater than 90°.

An acute triangle has all angles less than 90°.

A right triangle has one angle that is exactly 90°.

A marked ruler and a compass are essential for accurate triangle construction.

Measuring lengths incorrectly or not ensuring the triangle inequality can lead to failure in construction.

Triangles are named using their vertices. The order of the vertices can vary.