SOLUTION: how do you find the smallest angle of a triangle with sides 11cm, 13cm and 17cm?

Algebra ->  Triangles -> SOLUTION: how do you find the smallest angle of a triangle with sides 11cm, 13cm and 17cm?      Log On


   

Question 478114: how do you find the smallest angle of a triangle with sides 11cm, 13cm and 17cm?
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
The smallest angle should be the one opposite the shortest side, namely the side with length 7.
From the cosine law,
11%5E2+=+13%5E2+%2B+17%5E2+-+2%2A13%2A17%2AcosA
==> -337 = -442*cos A
==> A+=+cos%5E%28-1%29%28337%2F442%29
==> A = 40.32 degrees, to 2 decimal places.