Question

Please help using law of cosines!

Answer 1

∠ A ≈ 48°

Explanation:

Using the Cosine rule to find an angle

cosA =
`(b^2+c^2-a^2)/(2bc)`

with a = 10, b = 13 and c = 11

cosA =
`(13^2+11^2-10^2)/(2(13)(11))`

=
`(169+121-100)/(286)`

=
`(190)/(286)` , thus

A =
`cos^(-1)` (
`(190)/(286)` ) ≈ 48° ( to the nearest degree )