Question

Triangle ABC has an area of 25 square feet and a perimeter of 65.5 feet. △ABC is dilated by a factor of 5/2 to create △DEF. \

Calculate the area of ABC using the scale factor.

Calculate the perimeter of DEF using the scale factor.

Answer 1

Solution. To find the perimeter of \triangle ABC we use the Pythagorean Theorem which tells us that |AB|^2 = |AC|^2 + |BC|^2. Since |AC| = 5 and |BC| = 12 we find that |AB| = \sqrt{169} = 13. The perimeter of \triangle ABC is then 5 + 12 + 13 = 30 units.