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Middle Years

5.02 Cosine rule

Interactive practice questions

Which of the following is true for the given triangle?

$\cos\theta=\frac{b^2+a^2-c^2}{2bc}$cosθ=b2+a2c22bc

A

$\cos\theta=\frac{b^2+c^2-a^2}{2bc}$cosθ=b2+c2a22bc

B

$\cos\theta=\frac{b^2+c^2-a^2}{2ab}$cosθ=b2+c2a22ab

C

$\cos\theta=\frac{a^2+c^2-b^2}{2bc}$cosθ=a2+c2b22bc

D
Easy
< 1min

To use the cosine rule to find the length of $AC$AC, which angle would need to be given?

Easy
< 1min

Find the length of $a$a using the cosine rule.

Round your answer to two decimal places.

Medium
3min

Find the length of $a$a using the cosine rule.

Round your answer to two decimal places.

Medium
2min
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