You can assume that a figure is drawn to scale unless the problem says otherwise. So, when
you’re stuck on a geometry question and don’t know what else to do, see if you can at least
use your eyes to eliminate a few answer choices as visibly too small or too big.Eyeballing is never what you’re supposed to do to answer a question, but if you don’t see a better
way, eyeballing’s better than skipping.
THREE SPECIAL TRIANGLE TYPES
Three special triangle types deserve extra attention:
Be sure you know not just the definitions of these triangle types, but more importantly their special
characteristics: side relationships, angle relationships, and area formulas.
Isosceles triangle: An isosceles triangle is a triangle that has two equal sides. Not only are two sides
equal, but the angles opposite the equal sides, called base angles, are also equal.
Equilateral triangle: An equilateral triangle is a triangle that has three equal sides. Since all the
sides are equal, all the angles are also equal. All three angles in an equilateral triangle measure 60
degrees, regardless of the lengths of the sides. You can find the area of an equilateral triangle by
dividing it into two 30-60-90 triangles, or you can use this formula in terms of the length of one side
s:
Right triangle: A right triangle is a triangle with a right angle. The two sides that form the right
angle are called legs, and you can use them as the base and height to find the area of a right
triangle.
Isosceles triangles
Equilateral triangles
Right triangles