a circular mirror of radius 21 cm is surrounded by a circular frame of width 3.5 cm. find the cost of making the frame at ₹15 per cm
Answers
Answer:
Step-by-step explanation:
let radius of mirror [r] = 21 cm
circular frame of width 3.5 cm
∴radius of mirror + frame [R] = [21 cm +3.5cm] =24.5cm
Now area of the frame= The area of the region enclosed by two concentric circles is given by:- A = π (R^2 – r^2) Here, R = 24.5cm, r = 21 cm and π = 3.14
A = π (R^2 – r^2) = π (R – r)(R + r) cm^2
[applying (a^2 – b^2) = (a – b)(a + b)] identity
A = π (24.5^2 – 21^2) = 22/7 (24.5 – 21)(24.5 + 21) cm^2
A = π (24.5^2 – 21^2) = 22/7 *3.5*45.5 cm^2
A =22*0.5*45.5 =500.5 cm^2
cost of making frame for 1cm is 1.50
⇒total cost Rs 500.5 cm^2 *1.50 =Rs 750.75
Therefore rupees needed for framing the mirror=Rs 750.75 ANS
Answer:
Rs. 7507.50
Step-by-step explanation:
The following is the correct answer,,,,
The answer Is. 750.75 is wrong.