Question

Angle AOB is:

Options

• 60°

• 90°

• 45°

• None of these

Answer 1

None of these

Explanation:

By applying the Law of Cosines to $\triangle AOB$, we get:

`(angle AOB) = {5^2 + 13^2 - 12^2}{2 \times 5 \times 13} = {50}/{130} = {5}/{13}`.

Since arccos `({5}/{13})` ≈ 67.38°, the angle does not match 60°, 90°, or 45°.