RULES FOR AREA AND VOLUME OF DIFFERENT 
FIGURES 
Area of Square. Multiply the length of side by itself, 
or, as is said, “ square ” it. 
Area of Rectangle. Multiply the base by the altitude. 
Area of Parallelogram. (Figure A.) Multiply base a b 
by altitude b c, not by b d. If b d and the angle at d are 
known, b c may be found by the formula 
bc= bdX sine of angle at d. 
Area of Triangle. (Figure B.) Multiply base a b by 
altitude c d and divide by 2. 
Area of Triangle with 3 Sides Given. (Figure B.) Add 
the 3 sides together and divide the sum by 2. From this 
half sum take each side in succession. Multiply the half 
sum and the remainders all together and take the square 
root. The formula is 
Vi s (i 5 — a) (i s — b) (is — c) 
Circle. Circumference equals diameter X 3.1416. 
Area of Circle. (Figure C.) Square the diameter, 
multiply by 3.1416, and divide by 4. 
