Question

Find MN to the nearest tenth? A. 11.34 B. 16.1 C. 39.6 D. 23.8

Answer 1

As the question say this problem is a practice of the law of cosines!

The law of cosine: c^2=a^2+b^2-2ab*cos*c for any side a, b and c

The law can also be written as c=sqrt(a^2+b^2-2abcosc)

Now use this formula!(note cos 100 degrees is about 0.8623)

c=sqrt(15^2+16^2-2*15*16*cos100)

solving this we can MN is about 23.75

Round this to the nearest tenths now!

We get 23.8!

Thus the answer is D