The figure is not drawn to scale. Three pentagons R, S and T are arranged as shown in the figure. The area of Pentagon R is
25 the area of Pentagon S. The area of Pentagon S is
25 the area of Pentagon T.
(a) Find the ratio of the area of Pentagon R to the area of Pentagon T.
(b)
34 of Pentagon R is shaded. What fraction of the whole figure is not shaded?
R |
S |
T |
2x2 |
5x2 |
|
|
2x5 |
5x5 |
4 u |
10 u |
25 u |
(a)
Area of Pentagon S is the repeated identity. Make the area of Pentagon S the same. LCM of 5 and 2 is 10.
Pentagon R : Pentagon T
4 : 25
(b)
Shaded part of Pentagon R
=
34 x 4 u
= 3 u
Unshaded part of Pentagon R
= 4 u - 3 u
= 1 u
Unshaded part of Pentagon T
= 25 u - 3 u
= 22 u
Total figure unshaded
= 22 u + 1 u
= 23 u
Total figure
= 25 u + 1 u
= 26 u
Fraction of the whole figure that is unshaded
=
2326Answer(s): (a) 4 : 25; (b)
2326