Question

Suppose a triangle has two sides of length 3 and 4 and that the angle between these two sides is . What is the length of the third side of the triangle?

Answer 1

what's the angle there ?

Answer 2

@freddyloco
I'm assuming this is a right triangle.
for right triangles, there are special cases for some triangles where every side of a triangle is a whole number.
the numbers 3 and 4 are part of this special group of triangles.
it is called a 3-4-5 triangle, it looks like this:

does this make sense?

Answer 3

oh haha,
ignore what I just said..

Answer 4

so this?

Answer 5

law of cosine is like this:

a^2 = b^2+c^2 - 2bc Cos(angleA)
can you pick out the side lenghts for 'b' and 'c' and the angle for A we should use in the equation to find the length of the missing side?

Answer 6

I don't know how to do this but I just put a picture up of the question

Answer 7

I saw the attachement you had of the screen shot..

Answer 8

yea

Answer 9

this whole question is about the law of cosine. thats all,
this question is just seeing if you know how to use the law of cosine

I can teach you how to use it if yo don't know how ^_^
its actually really easy

Answer 10

ok how?

Answer 11

is it 3?

Answer 12

a^2 = b^2+c^2 - 2bc Cos(angleA)

in the law of cosine formula,
the lower case letters mean lengths of side
the capital Letters mean the angle to the opposide side of the length, like this:

Answer 13

make sense so far?
so lower case a means the length of that side of the triangle
and capital A means the angle
so, if I said lets have a=10 and A=50degrees, then they would fit onto the triangle like this:

easy enough right?

Answer 14

so going back to the idea of lower case and capital letters: