iemisc (version 0.9.9)

righttri: Right triangle calculations

Description

This function computes the missing length (must have at least 2 sides) and the interior angles (degrees) of a right triangle.

Usage

righttri(a = NULL, b = NULL, c = NULL)

Value

list of known sides a, b, and c & the interior angles A, B, and C (right angle), in degrees, if and only if the given sides create a right triangle.

Arguments

a

numeric vector that contains the known side a, if known

b

numeric vector that contains the known side b, if known

c

numeric vector that contains the known side c (hypotenuse), if known

Details

Side a is the side adjacent to angle B and opposite angle A. Side b is the side adjacent to angle A and opposite angle B. Side c (hypotenuse) is opposite the right angle (angle C).

This function makes the following calculations:

1. the length of the missing side using the Pythagorean theorem,

2. the area of the right triangle,

3. the altitude of the right triangle,

4. the angle associated with the side named a (degrees),

5. the angle associated with the side named b (degrees), and

6. the angle associated with the side named c (degrees).

References

1. r - Better error message for stopifnot? - Stack Overflow answered by Andrie on Dec 1 2011. See https://stackoverflow.com/questions/8343509/better-error-message-for-stopifnot.

2. Masoud Olia, Ph.D., P.E. and Contributing Authors, Barron’s FE (Fundamentals of Engineering Exam), 3rd Edition, Hauppauge, New York: Barron’s Educational Series, Inc., 2015, page 44-45.

3. Wikimedia Foundation, Inc. Wikipedia, 28 December 2015, “Pythagorean theorem”, https://en.wikipedia.org/wiki/Pythagorean_theorem.

4. Wikimedia Foundation, Inc. Wikipedia, 26 November 2015, “Radian”, https://en.wikipedia.org/wiki/Radian.

5. Wikimedia Foundation, Inc. Wikipedia, 9 December 2015, “Right triangle”, https://en.wikipedia.org/wiki/Right_triangle.

Examples

library("iemisc")
if (FALSE) {
righttri(0, 2) # a = 0, b = 2

righttri(1, 2) # a = 1, b = 2

righttri(a = 5, c = 10)

righttri(a = 3, c = 5)

righttri(a = 5, c = 10)
}