Questions: Given the diagram, if Z is the incenter of triangle WXY, m angle WYX=86°, and m angle WXZ=33°, find the following measures:
m angle WYZ=
m angle WXY=
m angle YWX=
m angle ZWX=
Transcript text: Given the diagram, if $Z$ is the incenter of $\triangle W X Y, m \angle W Y X=86^{\circ}$, and $m \angle W X Z=33^{\circ}$, find the following measures:
\[
m \angle W Y Z=\square
\]
\[
m \angle W X Y=
\]
$\square$
\[
m \angle Y W X=
\]
$\square$
\[
m \angle Z W X=
\]
$\square$
Solution
Solution Steps
Step 1: Find m∠WYZ
Since Z is the incenter, YZ bisects ∠WYX. Therefore, m∠WYZ = m∠WYX / 2.
Given m∠WYX = 86°,
m∠WYZ = 86° / 2 = 43°
Step 2: Find m∠WXY
The sum of the angles in a triangle is 180°. In ΔWXY, we have
m∠WXY + m∠YWX + m∠WYX = 180°
m∠YWX = m∠WXZ + m∠ZWX
Given m∠WXZ = 33°
We know m∠WYX = 86°
Therefore,
m∠WXY + (33° + m∠ZWX) + 86° = 180°
m∠WXY + m∠ZWX = 180° - 86° - 33°
m∠WXY + m∠ZWX = 61°
Since Z is the incenter, XZ bisects ∠YXW. Therefore, m∠WXZ= m∠YXZ=33°. Similarly, WZ bisects ∠YWX and YZ bisects ∠WYX.
The measure of an angle formed by an angle bisector is equal to half the measure of the bisected angle. The measure of an angle formed by two angle bisectors is equal to 90° plus half the measure of the third angle.
Therefore,
m∠WXY = 1/2 (180° - 86°)= 1/2(94°) = 47°
m∠YWX = 1/2 (180° - m∠X) = 1/2 (94°) = 47° + 16°= 63°
So, m∠WXY = 61° - m∠ZWX= 47°