# trigonometry

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In the triangle ABC, the sides AB and BC have lengths 7cm and 8cm respectively, and angle B is obtuse. the area of the triangle is 14 root 3 cm^2. Find
a.The size of angle B
b. The length of AC

• trigonometry -

formula for area of triangle
= (1/2)ab sinØ, where Ø is the contained angle of sides a and b

(1/2)(7)(8) sinØ = 14√3
sin Ø = 28√3/56 = √3/2
Ø = 60°

• trigonometry -

now use the cosine law to find AC

• trigonometry -

given triangle ABC with

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