How did I get 60?

a=b=c
c^2 = a^2 + b^2 - 2ab cos(t)
a^2 = a^2 + a^2 - 2a^2 cos(t)
a^2 = 2a^2 - 2a^2 cos(t)
1 = 2[1 - cos(t)]
cos(t) = 1/2
t=60

Question

How did I get 60?



a=b=c
c^2 = a^2 + b^2 - 2ab cos(t)
a^2 = a^2 + a^2 - 2a^2 cos(t) 
a^2 = 2a^2 - 2a^2 cos(t) 
1 = 2[1 - cos(t)] 
cos(t) = 1/2 
t=60

nnesha · Answer

how did you get 60??
i honestly don't know 
is there any a b or c valuez ?

zarkon · Answer

from the work you just did...what don't you understand?

it looks like you are using the law of cosines to verify that an equilateral triangle has interior angles of $60^\circ$ each