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deezy2x
18.07.2019 •
Mathematics
Find the measure of angle a in the triangle abc.
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Ответ:
43.531
Step-by-step explanation:
This problem needs the law of cosines since the three sides of the triangle are involved as well as one angle. The law of cosines is:
c^2 = a^2 + b^2 - 2ab*cos(C)
Where the lowercase letters are side values and capital letters are angle values. Just in case I will mention side a is the one with a length of 14, side b is 20 and c = 12.
Since it is asking for angle A instead of angle C we can rewrite the law of cosines to fit that, basically just rearranging the letters.
a^2 = c^2 + b^2 - 2cb*cos(A)
Now we just plug in and solve.
14^2 = 12^2 + 20^2 - 2*12*20*cos(A)
Rearrange to get A by itself
Now we take the inverse cosine, or arccos of both sides to get our answer.
Let me know if there is something in my explanation you don't understand.
Ответ: