TERMS FOR TRIANGLE PROBLEMS

Scalene Triangle: triangle with no equal sides and no equal angles
Isosceles Triangle: triangle with two equal sides and two equal angles
Equilateral Triangle: triangle with three equal sides and three equal angles
Right Triangle: triangle that contains a 90° angle

RULES FOR TRIANGLE PROBLEMS

1) Angle Rules:
      a) the sum of the angles in a triangle = 180°
      b) an exterior angle of a triangle equal the sum of the two opposite interior angles
      c) interior angles of a triangle are equal if their opposite sides are equal

                      If x = y, then b = c

2) Side Rules:

                    , so

3) Area Rule:
      a) area = (base)(height) / 2

              If h = 4 and b = 12, then area = 24.

SAMPLE PRACTICE QUESTION FOR TRIANGLES

1.

If STU is an isosceles triangle and TUD is 110°, then what is the value of (x - y)?

      Solution
      1) angle TUS and angle TUD form a straight angle, so TUS = 180° - 110° = 70°.

      2) Triangle STU is isosceles, so ST = TU and x = angle TUS = 70°.

      3) The internal angles of Triangle STU = 180°, so y = 180 - 2x --> y = 180 - 2(70) --> y = 40.

      4) (x - y) = (70 - 40) = 30

Math: Triangle Problems

Lesson Includes:

—Math Terms for Triangle Problems

—Rules for Triangle Problems

—Sample Practice Questions

—Practice Questions

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