## Qwerty90 3 years ago A student made the following chart to prove that AB2 + BC2 = AC2. Statement Justification 1. Triangle ABC is similar to triangle BDC 1. Angle ABC = Angle BDC and Angle BCA = Angle BCD 2. BC2 = AC × DC 2. BC ÷ DC = AC ÷ BC because triangle ABC is similar to triangle BDC 3. Triangle ABC is similar to triangle ABD 3. Angle ABC = Angle BAD and Angle BAC = Angle ABD 4. AB2 = AC × AD 4. AB ÷ AD = AC ÷ AB because triangle ABC is similar to triangle ABD 5. AB2 + BC2 = AC × AD + AC × DC = AC (AD + DC) 5. Adding Statement 1 and Statement 2 6. AB2 + BC2 = AC2

1. Qwerty90

2. Qwerty90

Which of the first four steps is the error

3. Qwerty90

I've already elimianted the first choice

4. Qwerty90

I think it is the 3rd one. what do you all think?

5. shivam_bhalla

@Qwerty90 , what makes you think that the 3rd option is wrong ??

6. shivam_bhalla

I'll tell you are right/wrong after you tell me your reason

7. Qwerty90

The angles don't correspond because they don't have the same angle?

8. shivam_bhalla

Good job @Qwerty90

9. Qwerty90

Thanks!

10. shivam_bhalla

yw :)