Question

Use the law of cosines to find the value of 2*3*4 cos theta.

Answer 1

by the cosine rule:
A^2 = B^2 + C^2 - 2BC cos A',
where A, B, C are the sides and cos A' is the cosine of the angle which is directly opposite a specified side.

In the diagram, cos A' = cos (theta),
A = 2, B = 3, C = 4.
Subbing in:
2^2 = 3^2 + 4^2 - 2(3)(4) cos (theta)
2(3)(4) cos (theta) = 3^2 + 4^2 - 2^2 = ?

Answer 2

21?

Answer 3

@dauspex

Answer 4

21 IS CORRECT!!!

Answer 5

Yes