Listen NCERT Audio Books to boost your productivity and retention power by 2X.
Find the area of a ring whose outer and inner radii are respectively 23 cm and 12 cm.
Consider the ring as shown in the figure below,
The inner radius of ring is ‘r’ and the outer radius is ‘R’.
Area of inner Circle = πr2 and Area of outer Circle = πR2
Where r = 12 cm and R = 23 cm
Area of ring = Area of outer circle – Area of inner circle
Area o ring = πR2 – πr2 (put values of r & R)
⇒ Area of ring = π(232) – π(122)
⇒ Area of ring = π(232 – 122) (taking π common from R.H.S)
⇒ Area of ring = π(529 – 144)
= 1210 cm2
Area of ring is 1210 cm2.
ABCD is a field in the shape of a trapezium, AD || BC, ∠ABC = 90° and ∠ADC = 60°. Four sectors are formed with centres A, B, C and D, as shown in the figure. The radius of each sector is 14 m.
Find the following:
(i) total area of the four sectors,
(ii) area of the remaining portion, given that AD = 55 m, BC = 45 m and AB = 30 m.
A child draws the figure of an aeroplane as shown. Here, the wings ABCD and FGHI are parallelograms, the tail DEF is an isosceles triangle, the cockpit CKI is a semicircle and CDFI is a square. In the given figure, BP ⊥ CD, HQ ⊥ FI and EL ⊥ DF. If CD = 8 cm, BP = HQ = 4 cm and DE = EF = 5 cm, find the area of the whole figure. [Take π = 3.14.]