SOLUTION: i have a triangle with sides 8,7, 10 . i must find the measure of the angle opposite of side 10. please help if possible. thank you

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Question 299857: i have a triangle with sides 8,7, 10 . i must find the measure of the angle opposite of side 10. please help if possible. thank you
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
: i have a triangle with sides 8,7, 10 . i must find the measure of the angle opposite of side 10. please help if possible. thank you
:
We can use the law of cosines here
Assign the sides as follows
a=8, b=7, c=10, then C = angle opposite 10
:
a^2 + b^2 - 2bc*cos(C) = c^2
using the above values
8^2 + 7^2 - 2(8*7) * cos(C) = 10^2
64 + 49 - 2(56)*cos(C) = 100
113 - 112*cos(C) = 100
-112*cos(C) = 100 - 113
cos(C) = -13%2F-112
cos(C) = +.11607
C = 83.33 degrees
:
That's the procedure, but check my math