
Diyu P. answered 04/01/25
Patient MD, Ivy-League Geometry Tutor with 10+ years of experience
To find the area of the composite figure, sum the area of the triangle ABC, the area of the parallelogram ACDF, and the area of the sector FDE.
1) Find the area of the triangle ABC
Area of a triangle is given by the formula: A = 1/2 * b * h
b = 4cm
h = 3cm
A = 1/2 * 4cm * 3cm = 6 sq cm
2) Find the area of the parallelogram ACDF
Area of a parallelogram is given by the following formula:
A = b*h, where b is the base, and h is the line drawn perpendicular to two parallel edges
b = 20 cm
h = 4 cm (given to use by the triangle)
A = 20cm * 4cm = 80 sq cm
3) Find the area of the sector FDE
The area of the sector is the area of the fraction of the circle it makes, based off the labeled angle.
Asector = fraction of the circle * Acircle
The area of the whole circle can be given by:
Acircle = πr2
What is the radius?
In this case, the radius is the same the edge of the parallelogram that wasn't labeled. By definition of a parallelogram, edge DF is the same length as AC. AC is also the hypotenuse of the triangle. Because ABC is a right triangle with lengths 3 cm and 4 cm, we can use the 3-4-5 Pythagorean triple to ascertain that the hypotenuse is 5cm. We could also use the Pythagorean theorem for this 32 + 42 = c2
So the whole circle's area Acircle = π(5cm)2 = 25π sq cm
Thus the sector's area is Asector = 35/360*Acircle =35/360*(25π sq cm) = 875π/360 sq cm
4) Add these all together
Acomposite = Atriangle + Aparallelogram + Asector
Acomposite = 6 sq cm + 80 sq cm + 875π/360 sq cm
Acomposite ≅ 93.59 sq cm
So the area of the entire composite figure is about 93.59 sq cm
Jash J.
So acdf + edf03/31/25