15. Triangles ABC and DEF are similar.
Work out the length of BC.
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10cm

Step-by-step explanation:

Since ABC and DEF are similar, the ratio of their side is always the same.

The ratio here is:

DF/AC = 6/4 = 1.5

Therefore, it means that BC x 1.5 = EF

So:

BC x 1.5 = 15

BC = 15 / 1.5 = 10cm.

dc=6 square root of 3 and ac is 12 square root 3

c and d

step-by-step explanation:

square root of 3/2 = 18/c

cross multiply to get 18*2=√3*c

36/√3 * √3/√3 = c

c= 36*√3/3

c=12√3