What is the length of angle MN, to the nearest tenth of a foot?
a. 10.6 ft
b. 14.7 ft
c. 15.6 ft
d. 18.0 ft

The length of the side MN is 14.7 ft
The given parameters are:
MP = 10 ft
PN = 13 ft
Angle P = 78 degrees
To determine the length MN, we make use of the following cosine law
[tex]c^2 = a^2 + b^2 -2ab * cos C[/tex]
So, we have:
[tex]c^2 = 13^2 + 10^2 -2*13*10 * cos(78)[/tex]
Evaluate the exponents, and the products
[tex]c^2 = 169 + 100 - (260 * 0.20791)[/tex]
Evaluate the sum and the product
[tex]c^2 = 269 - 54.0566[/tex]
Evaluate the difference
[tex]c^2 = 214.9434[/tex]
Take the square root of both sides
[tex]c = 14.6609481276[/tex]
Approximate
[tex]c = 14.7[/tex]
Hence, the length of the side MN is 14.7 ft
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