Non-right-angled Triangles

Summary

the trigonometric methods given earlier apply only to triangles containing a right angle.

for triangles without a right angle, the sine rule, the cosine rule and the area formula can be used to solve triangles and find their areas.

Key Skills

  • use the sine rule to solve triangles where two sides and one opposite angle or two angles and one opposite sideare given.
  • use the cosine rule to solve triangles where two sides and the included angle or three sides are given.
  • find the area of a non-right-angled triangle using the area formula.

Vocabulary

sine rulecosine rulearea formula.