Suman made a picture with some white paper and a single coloured paper as shown in the figure white paper is available at home and free of cost the cost of colour paper used is at 10 P per centimetre square find the total cost of colour paper used
Answers
Answer:
14.92 is the answer.......
Answer:
Consider the triangular sheet whose each side is 10cm long.
We know that the area of equilateral triangle =
4
3
side
2
=
4
3
(10)
2
=25
3
cm
2
So, A
1
= 25
3
cm
2
Now, consider the two identical triangular strip having sides 10cm,9cm and 3cm, respectively.
Here, we have a=10cm,b=9cm and c=3cm.
Semi-perimeter, s=
2
a+b+c
=
2
10cm+9cm+3cm
=11cm
Area of the triangle =
11×(11−10)×(11−9)×(11−3)
cm
2
=
11×1×2×8
=4
11
cm
2
So, area of two identical triangular strips, A
2
=2×4
11
cm
2
=8
11
cm
2
Again, consider the two identical triangular strip having sides 20cm,20cm and 4cm, respectively.
Here, we have a=20cm,b=20cm and c=4cm
Semi-perimeter, s=
2
a+b+c
=
2
20cm+20cm+4cm
=22cm
Area of the triangle =
22×(22−20)×(22−20)×(22−4)
cm
2
=
22×2×2×18
=12
11
cm
2
So, area of two identical triangular strip, A
3
=2×12
11
cm
2
=24
11
cm
2
Therefore, area of total black coloured sheet used =A
1
+A
2
+A
3
=25
3
cm
2
+8
11
cm
2
+24
11
cm
2
=25
3
cm
2
+32
11
cm
2
=25×1.732+32×3.31=149.22cm
2
Given, cost of black paper used per cm
2
=10 paise or Rs.0.1
So, cost of using 149.22cm
2
of black paper =Rs.0.1×149.22=Rs.14.92