Question

Geometry help? proofs?

Answer 1

yeah basically. or just go like:
Statement (proof/reason)

Answer 2

example:
a + c = b + c (Addition Property of Equality)

Answer 3

All right, so you have:
1. \(m\angle ABD = m\angle ACB=45\deg\)........(given)

2. \(\therefore\angle ABD \cong \angle ACB\).......(from 1, def. of congruent angles)


what else.... @Samosith

Answer 4

Would I use the Side-angle-side postulate anywhere, @PaxPolaris ?

Answer 5

you can use SSS / SAS / AA to prove similarities....

you need two pairs of sides with the same ratio for SAS ... you don't have that here

Answer 6

apart from the given angles ... the two triangles share a common angle

Answer 7

Both triangles have a 45 degree angle, and both triangles share the angle BCA- call it x,
therfore the missing angle in each triangle is 180=(45+x) which you'll note is equal for both triangles, now you have two triangles with 3 angles equal.

Answer 8

Sorry, i mean the angle BAC is shared by both triangles

Answer 9

The course I am taking is making me put a lot of "fluff" in the proofs. more than necessary.

Answer 10

and the missing angle is found by 180-(45+x) not =....very bad typing on my part!

Answer 11

<ABD=45=<BCA
<BAC is common to both triangle ABC and ABD
Thus as the two triangles have two equal angles, they are similar.
I dont know about two columns, but that proof should suffice, just put the triangle symbol instead of the word triangle.

Answer 12

and perhaps write (given) next to the first line

Answer 13

right.. so you have:
3. \(\angle BAD \cong \angle CAB \) .......(different names for same angle)
4.\[\therefore \triangle ADB \cong \triangle ABC\].......(from 2-3, AA postulate/theorem/whatever)

Answer 14

awesome. Thanks. I have been rushing through this part of the course because I need to finish by tomorrow. So I haven't had much time to actually /learn/ the material as much as would normally.

Is that all that is needed?

Answer 15

As *I* would normally***

Answer 16

yes ...

Answer 17

great. thank you.