Question

To prepare for a triathlon, Amanda starts from position A and rides her bike along a straight road for 12 miles to reach position B. At B, she turns left and rides along another straight road for 15 miles to reach position C. At C, she turns left again and rides 20 miles along a straight road to return to A. In , what are m∠A, m∠B, and m∠C, respectively?

Answer 1

48.35°, 94.94°, 36.71°

Explanation:

Answer 2

Explanation:

Let's draw the given information first for better understanding . Check the image attached.

We can use cosine rule to find the angles .

for angle A ,

`Cos A =(b^2+c^2-a^2)/(2bc)`

`Cos A =(20^2+12^2-15^2)/(2*20*12)`

`Cos A =(319)/(480)`

m∠A = 48.35 degrees

Similarly for angle B

`Cos B =(a^2+c^2-b^2)/(2bc)`

`Cos B =(15^2+12^2-20^2)/(2*15*12)`

`Cos B =(-31)/(360)`

m∠B = 94.94 degrees

Now use A+B+C=180 degrees

48.35+94.94+C=180

C=180-48.35-94.94

m∠C = 36.71 degrees