8. Applications of Trigonometry

8.01 Solving right triangles

8.02 Applications using right triangle trigonometry

8.03 Right triangle applications in 3D

8.04 Law of sines

8.05 Law of cosines

8.06 Extension: Bearings

8.07 Extension: Degrees, minutes, seconds

8.08 Arc length and sector area

8.09 Linear and angular speed

United States of America

Grades 9-12

8.05 Law of cosines

Interactive practice questions

Find the length of $a$a using the law of cosines.

Round your answer to two decimal places.

A triangle with its vertices labeled as A, B, and C. The angle at vertex A measures $33^\circ$33°. The side opposite to the $33^\circ$33° angle, side $BC$BC, is labeled $a$a units, indicating its unknown length. Side $AB$AB measures $30$30 units, as shown by the scale line beneath it. Side $AC$AC measures $13$13 units. Side $AB$AB and Side $AC$AC are adjacent to the $33^\circ$33° angle at vertex A.

Easy

3min

Find the length of $a$a using the law of cosines.

Round your answer to two decimal places.

Easy

2min

Find the length of $a$a using the law of cosines.

Round your answer to two decimal places.

Easy

2min

Find the length of $q$q using the law of cosines.

Round your answer to two decimal places.

Easy

2min

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