The figure is not drawn to scale. Three pentagons K, L and M are arranged as shown in the figure. The area of Pentagon K is
23 the area of Pentagon L. The area of Pentagon L is
25 the area of Pentagon M.
(a) Find the ratio of the area of Pentagon K to the area of Pentagon M.
(b)
34 of Pentagon K is shaded. What fraction of the whole figure is not shaded?
K |
L |
M |
2x2 |
3x2 |
|
|
2x3 |
5x3 |
4 u |
6 u |
15 u |
(a)
Area of Pentagon L is the repeated identity. Make the area of Pentagon L the same. LCM of 3 and 2 is 6.
Pentagon K : Pentagon M
4 : 15
(b)
Shaded part of Pentagon K
=
34 x 4 u
= 3 u
Unshaded part of Pentagon K
= 4 u - 3 u
= 1 u
Unshaded part of Pentagon M
= 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