Answer:
[tex]m\angle B=34\°[/tex]
Step-by-step explanation:
Given measures of 2 angles of a triangle :
m∠A = 69°
m∠C = 79°
Find m∠B.
We know that sum of angles of a triangle =180°
So, we have
[tex]m\angle A+m\angle B+m\angle C=180\°[/tex]
Substituting the vales of m∠A = 69° and m∠C = 79°
[tex]69\°+m\angle B+77\°=180\°[/tex]
Adding like terms.
[tex]m\angle B+146\°=180\°[/tex]
Subtracting both sides by 146°.
[tex]m\angle B+146\°-146\°=180\°-146\°[/tex]
∴ [tex]m\angle B=34\°[/tex] (Answer)
