Question

Geometry help please! I'm stuck!

Answer 1

This seems almost trivial - the triangles are evidently congruent - they have the same 3 angles and 1 common side.

You may use the sine rule to 'prove' this - but it seems a 'circular' argument.

Answer 2

(You know that the right angle and the marked angle are the same in both triangles - so the 3rd angle must also be the same)

Answer 3

that's why i'm having trouble. I know my teacher wants me to write out an entire proof but i have no clue where to start

Answer 4

Given:

Answer 5

it doesn't state a given.

Answer 6

You can use an angle theorem

Start off with stating the givens

Answer 7

okay so is the first one <DAB is congruent to <CBA by given?

Answer 8

Kinda. When I was in school we always put the central angle's letter in the middle. I'd write
\[\large DBA \cong CAB\]

Answer 9

okay. so is the first one that the right angles are equal? by given

Answer 10

Yes. That's what the statement \[\large DBA \cong CAB\] meant. The two right angles are congruent

Answer 11

okay. and then would it be the other angles, DAB and CBA by given, or by the theorem link you sent?

Answer 12

Yeah, the second one. that's all you need for the alternative interior angles.

As long as you can prove the angles are equal the lines will never touch.

Answer 13

so step 2 is the lines are aparellel because of whatever the name of the theorem is

Answer 14

okay, how do i find out the name of the theorem?

Answer 15

Do you have a textbook? it might be in there. I think it's just called Alternate Interior Angles

Answer 16

okay, i will look. thank you!