SOLUTION: find angle A of the oblique triangle with sides a=13, b=14, and c=15: find angle A of the oblique triangle with sides a=13, b=14, and c=15 Answer by mducky2(13) (Show Source):

Question 151214: find angle A of the oblique triangle with sides a=13, b=14, and c=15: find angle A of the oblique triangle with sides a=13, b=14, and c=15
Answer by mducky2(13) (Show Source):
You can put this solution on YOUR website!
If you need to find an angle when three sides of an oblique triangle are known, use the law of cosines. The equation is:
a2 = b2 + c2 - 2bc cos A
Solve for A
2bc cos A = b2 + c2 - a2
cos A = (b2 + c2 - a2)/(2bc)
A = cos-1[(b2 + c2 - a2)/(2bc)]
A = cos-1[(142 + 152 - 132)/(2*14*15)]
A = 53.13�
Ok now here is my choices
A. 53 Degrees 8' 48''
B 53 Degrees 8' 13''
C. 53 Degrees 7' 48''
D. 53 Degrees 7' 13''
How do I know which one it is?
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
It looks like the answer is correct (I haven't looked over the problem completely). So to convert 53.13� into degrees minutes and seconds, simply take the decimal portion 0.13 and multiply it by 60 to get . So there are about 7 minutes in 0.13 degrees. Now take the decimal portion 0.8 and multiply it by 60 to get . So there are 48 seconds in 0.8 minutes.

So 53.13� is the same as 53 degrees 7 minutes 48 seconds. So the answer is C.

Here is a good calculator to check your work with (it's towards the bottom of the page).
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