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AREAS AND VOLUMES. Mathematical formula for area calculation:. Area= ½ ( b×h ) Area = ½ (a ×c ×sinB ) Area =√s(s-a)(s-b)(s-c) s=(a+b+c)/2. Area = a². Area = a×b. Area= π r². Area = ½ ((a+b)/2)h. Area=1/4 n.a² cot(180º/n). Area= π (r 2 ² - r 1 ²). Area=(∆ / 360). π .r².
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Mathematical formula for area calculation: Area= ½( b×h ) Area = ½ (a ×c ×sinB ) Area =√s(s-a)(s-b)(s-c) s=(a+b+c)/2 Area = a² Area = a×b Area=π r² Area = ½ ((a+b)/2)h Area=1/4 n.a² cot(180º/n) Area=π(r2² - r1²) Area=(∆ / 360).π.r² Area = ½ r²((π∆/180)-sin∆) Area= 2/3 .b .h Area= π.a.b
Areas by the method of coordinates: y y x Y1x2 x1y2 Y2x3 x2y3 Y3x4 x3y4 Y4x5 x4y5 Y5x1 x5y1 x Area = ½ ( (y1x2 + y2x3+ y3x4 + y4x5 + y5x1) – (x1y2 + x2y3 + x3y4 + x4y5 + x5y1)) = ½ ( x1(y5-y2) + x2(y1-y3) + x3(y2-y4) + x4(y3- y5) + x5( y4-y1) )
y x x y
Areas of irregular figures: Trapezoidal rule:
Calculation of volumes: All highways and railroad construction projects involve Earthworks( Cut & Fill ) There are two methods to calculate the volumes of cut and fill.
Volume From Contour Maps The figure
Volume From Spot Levels The following figure Volume (V) = (A / 4)(∑h1 + ∑2h2 + ∑3h3 + ∑4h4 ) where A is the area of one rectangle or square and h1,h2,h3,h4 are the corner heights common to one, two, three and four rectangles respectively. Solution