Proof problem.

[box]

hey guys,I just ran into another proof problem that I cant seem to get.

Given=M1 + M3=180
prove M2=m3

1 m1+m3=180 given
2 m2+m3=180 linear pair postulate
3 m1+3=2+3 substitution property of equality
4 m3=m3 reflexive property of equality
5 m1=m2 subtraction property of equality

This was the answer given by the textbook,but I've realize m2 can never be equal to m3 because of the way the lines intercept.Could this be a textbook error?

 

[Steven G]

hey guys,I just ran into another proof problem that I cant seem to get.

Given=M1 + M3=180
prove M2=m3

1 m1+m3=180 given
2 m2+m3=180 linear pair postulate
3 m1+3=2+3 substitution property of equality
4 m3=m3 reflexive property of equality
5 m1=m2 subtraction property of equality

This was the answer given by the textbook,but I've realize m2 can never be equal to m3 because of the way the lines intercept.Could this be a textbook error?

You are correct that m2 can never equal m3 given that m1 + m2 = 180

 

[Ishuda]

hey guys,I just ran into another proof problem that I cant seem to get.

Given=M1 + M3=180
prove M2=m3

1 m1+m3=180 given
2 m2+m3=180 linear pair postulate
3 m1+3=2+3 substitution property of equality
4 m3=m3 reflexive property of equality
5 m1=m2 subtraction property of equality

This was the answer given by the textbook,but I've realize m2 can never be equal to m3 because of the way the lines intercept.Could this be a textbook error?

As Jomo implied, I also suspect it should have been
Given=M1 + M3=180
prove M2=m1
as you have done.