Question

what is the perimeter of the semicircle which circumscribes a right angled triangle in which the lengths of perpendicular sides are 15 cm and 20 cm ? (use π=3.14)​

Answer 1

Answer:

Let ABC be the right triangle, right angled triangle at A, whose sides AB and AC measures 6 cm and 8 cm respectively.

∴ Hypotenuse BC= (15) 2+(20) 2= 225=25cm

AO(A'O) is the radius of the common base of the double cone fanned by revolving the triangle around BC.

Area of ΔABC= 21×15×20= 21

BC×AO.

⇒150= 21 ×25×AO

⇒AO=12cm

Volume of the double cone

= 31π×AO

2×BO+ 3π×AO 2×CO

= 31π×AO

2(BO+CO)

= 31π×AO 2 ×BC

= 31×3.14×12×12×25=3768cm

3

Surface area of the double cone

=π×AO×AB+π×AO×AC

=π×AO(AB+AC)

=3.14×12×(15+20)

=3.14×12×35=1318.8cm

2