Question

what is $m\angle 1$?
triangle with angle 34° at the top, angle 1 at the bottom right, and an exterior angle of 147° at the bottom left
$m\angle 1 = \square ^\circ$
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Explanation:

Step1: Find adjacent interior angle

The 147° angle is supplementary to its adjacent interior angle of the triangle.
$180^\circ - 147^\circ = 33^\circ$

Step2: Use triangle exterior angle theorem

The measure of $\angle 1$ equals the sum of the two non-adjacent interior angles of the triangle.
$m\angle 1 = 34^\circ + 33^\circ$

Answer:

$111^\circ$