Math help please.. number 13
1 answer:
Use the Law of Cosines here with angle A as your reference angle. It will be the one that the helicopter is at, the one we are looking for. If that angle is angle A, then the side across from it is a, measure of 11.4. Here's how the Law looks in our particular situation: 
. Simplifying a bit we get 129.96 = 54.76 + 72.25 - 125.8cos(A) Combining like terms across the equals sign gives us 2.95 = -125.8 cosA. Doing the division we get -.0234499205 = cosA. Find the angle using the 2nd and cos buttons on your calculator. It's 91.34°, rounded to just 91°. Choice A
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Option 3:
m∠ABC = 66°
Solution:
Given and ABH is a transversal line.
m∠FAB = 48° and m∠ECB = 18°
m∠ECB = m∠HCB = 18°
<u>Property of parallel lines: </u>
<em>If two parallel lines cut by a transversal, then the alternate interior angles are equal.</em>
m∠FAB = m∠BHC
48° = m∠BHC
m∠BHC = 48°
<u>Exterior angle of a triangle theorem: </u>
<em>An exterior angle of a triangle is equal to the sum of the opposite interior angles.</em>
m∠ABC = m∠BHC + m∠HCB
m∠ABC = 48° + 18°
m∠ABC = 66°
Option 3 is the correct answer.