The product of side length and altitude is area. The area remains the same regardless of how you measure it.
From the first side and altitude, .. area = side*altitude = (4.2 cm)*(3.6 cm) = 15.12 cm^2 From the second side and altitude .. area = side*altitude .. 15.12 cm^2 = side*(2.4 cm) .. side = (15.12 cm^2)/(2.4 cm) = 6.3 cm
The perimeter is the sum of the measures of all sides. Opposite sides are of equal measure. .. perimeter = 2*(4.2 cm +6.3 cm) = 21.0 cm
