Answer
$H$
Work Step by Step
We will use the triangle sum theorem to find the measure of the third angle. The triangle sum theorem states that the measure of all three interior angles of a triangle equal $180^{\circ}$. Let's set $x$ equal to the measure of the third angle and set up the equation:
$43 + 38 + x = 180$
Add the constants on the left together:
$81 + x = 180$
Subtract $81$ from each side of the equation to solve for $x$:
$x = 99$
The measure of the third angle is $99$. This corresponds to option $H$.
