- #1
- 1,866
- 34
Homework Statement
In triangle ABC where you only know the sides: a, b and c I must find angle B.
a=8
b=6
c=12
Homework Equations
Law of cosines: c^2 = a^2 + b^2 -2ab*cos(C)
When angle C is at the opposite of side c, (same for a and b)
The Attempt at a Solution
12^2 = 6^2 + 8^2 -2*6*8*cos(C)
144 = 36+64-96cos(C)
44=-96cos(C)
-(44/96) = cos(C)
- (11/24) = cos(C)
(I know the answer is supposed to be 117.4)
And cos(117.4)=-(11/24)
The problem is:
How do I find the angle? The explanation says: "Use calculator (degree mode)"
How do I do that?
I have an TI-84 Plus