if two sides of right angled triangle are 3 cm and 4 cn other than hypotenuse find the area of triangle
Answers
Answer:
A right triangle, whose sides are 3 cm and 4 cm (other than hypotenuse) is made to revolve about its hypotenuse.
The volume and surface area of the double cone so formed are 30.144 cm³ and 52.75 cm² respectively.
Answer:
Step-by-step explanation:
Solution
The double cone so formed by revolving this right-angled triangle ABC about its hypotenuse is shown in the figure.
Hypotenuse, AC =
3
2
+4
2
=
9+16
=
25
=5 cm
Area of ΔABC=
2
1
×AB×AC
⇒
2
1
×AC×DB=
2
1
×4×3
⇒
2
1
×5×DB=6
So, DB =
5
12
=2.4 cm
The volume of double cone = Volume of cone 1 + Volume of cone 2
=
3
1
πr
2
h
1
+
3
1
πr
2
h
2
=
3
1
πr
2
[h
1
+h
2
]=
3
1
πr
2
[DA+DC]
=
3
1
×3.14×2.4
2
×5
=30.14 cm
3
The surface area of double cone = Surface area of cone 1 + Surface area of cone 2
=πrl
1
+πrl
2
=πr[4+3]=3.14×2.4×7
=52.75 cm
2