An iron pipe 20cm long has exterior diameter equal to 25cm.if the thickness of the pipe is 1cm , the pipe is to be painted red on all its faces . find the area to be painted.

An iron pipe 20cm long has exterior diameter equal to 25cm.if the thic

1.	An iron pipe 20cm long has exterior diameter equal to 25cm.if the thickness of the pipe is 1cm , the pipe is to be painted red on all its faces . find the area to be painted.
Answer» : Total surface area of pipe is 3168 cm²Given :height of pipe = 20cmExternal diameter = 25cmTo find :Area Solution :Given that height is 20CM , External diameter is EQUAL to 25cm . if the thickness of the pipe is 1cm so pipe painted red on all the faces . so we have to find the external radius and INTERNAL radius then after we have to use the formula of total surface area then we get the total surface area of pipe External diameter = 25cmExternal radius = 25/2 = 12.5 cmInternal diameter = 25 - (1 + 1) = 23 cmInternal radius = 23/2 = 11.5 cmLet the external radius be RLet the internal radius be RAS we know that :TSA of the pipe = 2πh(R + r) + 2π(R²+r²)TSA means total surface areawhere h is 20cm , R is 12.5cm , r is 11.5cm ⟿ 2 × 22/7 × 20(12.5 + 11.5) + 2 x 22/7(12.5² + 11.5²)⟿ (44 × 480)/7 + (44 × 24)/7⟿ 21120/7 + 1056/7⟿ 22176/7⟿ 3168cm²Hence , Total surface area of pipe is 3168 cm²