Explanation:
Given :-
- A triangle have two angles that measures 85° and 23°.
To Find :-
- Measure of the third angle.
Solution :-
Let the measure of the third angle of the triangle be x.
As we know that,
- The sum of all three sides of a triangle is 180° which is the angle sum property of triangle.
Therefore,
![\sf \longrightarrow {\angle{A}\ +\ \angle{B}\ +\ \angle{C}\ =\ 180^(\circ)}](https://img.qammunity.org/2023/formulas/mathematics/high-school/lvf0wfv31b9ung9cq9n1x0hupceu85f1vw.png)
![\sf \longrightarrow {85^(\circ)\ +\ 23^(\circ)\ +\ x\ =\ 180^(\circ)}](https://img.qammunity.org/2023/formulas/mathematics/high-school/b8pvxgdq6mp3fzdahte5oqdfp96cdw8xu6.png)
![\sf \longrightarrow {108^(\circ)\ +\ x\ =\ 180^(\circ)}](https://img.qammunity.org/2023/formulas/mathematics/high-school/jkzje2svzvnselcfjtwgz5fhrnvrikbjwh.png)
![\sf \longrightarrow {x\ =\ 180^(\circ)\ -\ 108^(\circ)}](https://img.qammunity.org/2023/formulas/mathematics/high-school/4jr7zihvvp1qdoum1z421ny5h1oub3rpfs.png)
![\bf \longrightarrow {\underline{x\ =\ 72^(\circ)}}\ \bigstar](https://img.qammunity.org/2023/formulas/mathematics/high-school/exaccnm08p4og1tgmronmg8se0puun1pp6.png)
∴ Hence, the measure of the third angle of the triangle is 72°.