Sine Rule & Cosine Rule

Drag the red dot to move the triangle.

Exercises for students:
Solve the following problems on paper and check your working using the above applet:

In triangle ABC, BC = 4 cm, AC = 5 cm, AB = 6 cm. Find the angles BAC, ABC and ACB.
In triangle ABC, BC = 4 cm, AC = 5 cm, angle ACB = 70°. Find the length of AB, and the angles BAC and ABC.
In triangle ABC, BC = 4 cm, angle BAC = 50°, angle ABC = 60°. Find the length of AC & AB, and the angle ACB.
In triangle ABC, BC = 4 cm, AC = 5 cm, angle BAC = 50°. Find the 2 possible values of angle ABC.


Summary
sin A / a = sin B / b = sin C / c
a² = b² + c² - 2bc cos A
The ambiguous case occurs when
2 sides ( a & b ) and a non-included angle A are given
and b sin A < a < b


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