∆ABC is similar to ∆DEF. The ratio of the perimeter of ∆ABC to the perimeter of ∆DEF is 1 : 10. The longest side of ∆DEF measures 40 units.
The length of the longest side of ∆ABC is units. The ratio of the area of ∆ABC to the area of ∆DEF is .

Question

∆ABC is similar to ∆DEF. The ratio of the perimeter of ∆ABC to the perimeter of ∆DEF is 1 : 10. The longest side of ∆DEF measures 40 units.
The length of the longest side of ∆ABC is  units. The ratio of the area of ∆ABC to the area of ∆DEF is .

directrix · Answer

I think there may be a number missing here: >> The longest side ∆ABC is units.

The longest side of ∆ABC is (how many) units.

directrix · Answer

The ratio of the perimeters of two similar triangles is the same as the scale factor.

That means that the scale factor from ∆ABC i
 to ∆DEF is 1:10 or 1/10,

directrix · Answer

If two triangles are similar, the square of the scale factor of the two triangles is equal to the ratio of the areas of the two triangles.

The ratio of the area of ∆ABC to the area of ∆DEF is  ( 1/10 ) ^ 2 = ?

@Nigeria.Arnold1

jhonyy9 · Answer

The ratio of the perimeter of ∆ABC to the perimeter of ∆DEF is 1 : 10. The longest side of ∆DEF measures 40 units.

- so i think from this result the longest side of triangle ABC is 40*1/10 = 4 units
@Directrix your opinion please ?
- .. and again one posible case - i think - than these triangles are isoscele - in this case there have missed too one length of a side ?

@Directrix thank you for your contribution ,collaboration - and welcome from Romania - Transylvania - the home country where was live Dracula - then you like watching the horror moves so than you know it sure - i m here in visite my mather and my younger sister and her family - i m holiday till 29 martzie - than i will return in Hungary,city Budapest