Given:
In ΔOPQ, p = 180 inches, q = 120 inches and ∠O=171°.
To find:
The length of o, to the nearest inch.
Solution:
According to cosine formula,

Using cosine formula in ΔOPQ, we get

On substituting the values, we get




Taking square root on both sides.



Therefore, the length of o is about 299 inches.