Question

estimate the measure of this angle within 15°.

Explanation:

Step1: Compare to right angle

A right angle is $90^\circ$. This angle is larger than a right angle, so it is obtuse.

Step2: Estimate the extra degrees

The angle is about $30^\circ$ more than $90^\circ$. Calculate: $90^\circ + 30^\circ = 120^\circ$, which is within a $15^\circ$ margin of error (range $105^\circ$ to $135^\circ$).

Answer:

$120^\circ$ (range: $105^\circ$ to $135^\circ$)