Area Formulas
The standard notation for area is A.
Square
Let's a square side is long a then area formula is:
A = a.a = a2
Rectangle
Let's a rectangle sides are long a and b
A = a.b
Parallelogram
Let's palallelogram sides are long a and b and
ha is the altitude to the side a,
and hb is the altitude to the side b
Parallelogram area formula is:
A = a.ha = b.hb
Parallelogram area formula explained.(a java applet will be opened in a new window).
Trapezoid
Say the length of the parallel sides of a trapezoid are long a and b and the distance between the two bases is h(the trapezoid altitude). The area formula is:
A = ½(a + b)h
Triangle
ABC is triangle
A = ½(a.ha) = ½(b.hb) = ½(c.hc)
A = ½(ab.sinC) = ½(ac.sinB) = ½(bc.sinA)
p = ½(a + b + c)
A = ½(ab.sinC) = ½(ac.sinB) = ½(bc.sinA)
A = √p(p - a)(p - b)(p - c) - Heron formula
A = R2sinA.sinB.sinC = abc/4R
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