Date: 08/13/97 at 21:22:02 From: Anonymous Subject: Triangle Area How do you find the area of a triangle?
Date: 08/19/97 at 08:59:54 From: Doctor Rob Subject: Re: Triangle Area That depends on the information you are given. Let S be the area you want to find. Here are some cases, where first is stated the given information, then the formula for S: 1. The lengths of one side (or base) b and the altitude h perpendicular to it. S = b*h/2. 2. The lengths of two sides a and b, and the measure of the angle C between them. S = a*b*sin(C)/2. 3. The lengths of all three sides a, b, and c. Let s = (a+b+c)/2. S = Sqrt[s*(s-a)*(s-b)*(s-c)]. 4. The measure of two angles A and B, and the length of the side c between them. S = (c^2/2)*sin(A)*sin(B)/sin(A+B). Here sin(x) is the sine of angle x. Many calculators have a button to calculate the sine function. -Doctor Rob, The Math Forum Check out our web site! http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994-2013 The Math Forum