Given circle D, calculate the measure of arc AC if AD=16 and BD=13.

Answer:
18.66
Step-by-step explanation:
Using the pythagorean theorem:
a^2 + b^2 = c^2
a^2 + 13^2 = 16^2
a^2 + 169 = 256
a^2 = 87
a = 9.33
Since we need to figure out length AC and not just AB, we can multiply our answer by 2:
9.33 x 2 = 18.66
Answer:
71.32°
Step-by-step explanation:
The measure of angle ADB can be found using the trig relation ...
Cos = Adjacent/Hypotenuse
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cos(ADB) = DB/AD = 13/16
Using the inverse function, ...
∠ADB = arccos(13/16) ≈ 35.659°
Arc AC has the same measure as angle ADC, which is double the measure of angle ADB.
Arc AC = 2×35.659° = 71.318° ≈ 71.32°
The measure of arc AC is about 71.32°.
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Additional comment
The length of arc AC is the product of the radius and its radian measure:
length AC = (16)(71.32π/180) ≈ 19.92 . . . units