Definition of Terms, Continued
Triangles
A triangle is a plane figure bound by three straight sides, which form three
interior angles. The top of the triangle is the vertex. The height of a triangle
is referred to as the altitude. The bottom of a triangle is its base. The sum
of the three interior angles is always 180°. When all sides and all interior
angles (60°) are equal, the triangle is referred to as an equilateral triangle.
When two sides and two angles are equal, the triangle is an isosceles
triangle. A scalene triangle does not have any equal sides or angles. A right
triangle has one angle equal to 90° and the long side opposing that angle is
called the hypotenuse.
Figure 2-4 shows triangles.
Figure 2-4.—Triangles.
Continued on next page
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