Question

In this question, all lengths are in centimetres.

Given
AB: AC = 1:2
AB= 3x-4
AC= 2x + 12
show that
AC: BC = 2:3
BС= 7X-2

Answer 1

Explanation:

First find x:

AB:AC=1:2

2(3x-4)=2x+12

6x-8=2x+12

4x-8=12

4x=20

x=5

Substitute:

AC=2x+12

=(2x5)+12

=10+12

=22

BC=7x-2

=(7x5)-2

=35-2

=33

22/33=2/3

Therefore AC:BC = 2:3

Answer 2

Explanation:

AB/AC =1/2

(3x-4)/(2x+12)=1/2

2(3x-4) = 1(2x+12)

6x-8=2x+12

4x=20

X=5

AC/BC =3x-4/7x-2=22/33=2/3

AB/AC=3x-4/7x-2=22/33=2/3

AB/AC=3x-4/2x+12

6x-8=2x+12

You would get 4/5 still trying to work out the last mark