Question

A right angled triangle PQR where angle Q = 90° is rotated about QR and PQ .If QR = 16 cm and PR = 20 cm , compare the curved surface areas of the right circular cones so formed by the triangle

Answer 1

3:4 is  the ratio of curved surface areas of the right circular cones formed by rotaing about QR and PQ  where QR = 16 cm & PR = 20 cm Q = 90°

Step-by-step explanation:

PR=20cm = Hypotenuse

QR = 16 cm

PQ² = PR² - QR²

=> PQ² = 20² - 16²

=> PQ = 12

PQ = 12 cm Base  when the triangle is revolving about the side QR

Radius of cone = base = 12cm

Slant height = Hypotenuse = 20 cm

Curved suface area = π R L

= π  12 * 20

= 240 π

PR=20cm = Hypotenuse

QR = 16 cm = Base  when the triangle is revolving about the side PQ

Radius of cone = base = 16cm

Slant height = Hypotenuse = 20 cm

Curved suface area = π R L

= π 16 * 20

= 320  π

Ratio of Curved surface area  rotated about QR and PQ  =  240π / 320 π

= 3 /4

Learn More:

compare the curved surface areas of the right circular cones

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Answer 2

Answer:

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