MATHS 20PT URGENT

1.
a : b = 1/3 : 1/2
a : b = 2 : 3
3a = 2b
a = (2/3)b

b : c = 2 : 5
2c = 5b
c = (5/2)b

a : b : c
= (2/3)b : b : (5/2)b
= (2/3)x6 : 1x6 : (5/2)x6
= 4 : 6 : 15


2.
a : b : c = 4 : 6 : 15
Let a, b and c be 4ko, 6ko and 15ko respectively.

The sum of the interior angles of a triangle is 180o,
thus a + b + c = 180o
4k + 6k + 15k = 180
25k = 180
k = 7.2

The greatest angle, c
= 7.2o x 15
= 108o
=

1.
a : b = 1/3 : 1/2
a / b = (1/3) / (1/2)
a / b = 2 / 3
a = 2b / 3

b : c = 2 : 5
b / c = 2 / 5
c = 5b / 2

a : b : c
= 2b / 3 : b : 5b / 2
= 2 / 3 : 1 : 5 / 2
= 4 : 6 : 15

2.
The largest angle
= 15 / (4 + 6 + 15) * 180
= 15 / 25 * 180
= 108 degree