Question

The length of yhe side of a triangle are 3:4:5 and its perimeter is 60 cm find its area

Answer 1

$Perimeter \: \: of \: \: triangle = a + b + c \\ \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 3x + 4x + 5x = 12x = 60 \\ \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = x = \frac{60}{12} = 5$

Hence,

1st side = 15 cm

2nd side = 20 cm

3rd side = 25 cm

Answer 2

let the first side = 3x

let the second side = 4x

let the third side = 5x

perimeter of triangle = sum of all sides

60 cm = 3x + 4x+ 5x

60 cm = 12 x

60 cm/12 =x

5cm =x

then ,

first side =3X5 =15cm

second side =4X5=20 cm

third side =5X5 =25

if ,

base is equal to 20 cm

and height is equal to 15cm

then ,

area of triangle =base X height

= 20 cm X 15 cm

= 300cm square