The figure is not drawn to scale. Three pentagons S, T and U are arranged as shown in the figure. The area of Pentagon S is
45 the area of Pentagon T. The area of Pentagon T is
13 the area of Pentagon U.
(a) Find the ratio of the area of Pentagon S to the area of Pentagon U.
(b)
34 of Pentagon S is shaded. What fraction of the whole figure is not shaded?
S |
T |
U |
4x1 |
5x1 |
|
|
1x5 |
3x5 |
4 u |
5 u |
15 u |
(a)
Area of Pentagon T is the repeated identity. Make the area of Pentagon T the same. LCM of 5 and 1 is 5.
Pentagon S : Pentagon U
4 : 15
(b)
Shaded part of Pentagon S
=
34 x 4 u
= 3 u
Unshaded part of Pentagon S
= 4 u - 3 u
= 1 u
Unshaded part of Pentagon U
= 15 u - 3 u
= 12 u
Total figure unshaded
= 12 u + 1 u
= 13 u
Total figure
= 15 u + 1 u
= 16 u
Fraction of the whole figure that is unshaded
=
1316Answer(s): (a) 4 : 15; (b)
1316