sat suite question viewer
In the figure above, and
intersect at point P,
, and
. What is the measure, in degrees, of
? (Disregard the degree symbol when gridding your answer.)
Explanation
The correct answer is 30. It is given that the measure of is
. Angle MPR and
are collinear and therefore are supplementary angles. This means that the sum of the two angle measures is
, and so the measure of
is
. The sum of the angles in a triangle is
. Subtracting the measure of
from
yields the sum of the other angles in the triangle MPR. Since
, the sum of the measures of
and
is
. It is given that
, so it follows that triangle MPR is isosceles. Therefore
and
must be congruent. Since the sum of the measure of these two angles is
, it follows that the measure of each angle is
.
An alternate approach would be to use the exterior angle theorem, noting that the measure of is equal to the sum of the measures of
and
. Since both angles are equal, each of them has a measure of
.