Trigonometry comes up in many aspects of biology. One example is X-ray crystallography, a technique used to determine the three dimensional structure of molecules. X-ray crystallography has been used to determine the atomic structure of thousands of biologically important molecules including vitamins, proteins, and perhaps most famously DNA. X-ray crystallography exploits the fact that when an x-ray is passed through a crystal, it is diffracted according the crystal's atomic structure.
The structure of a crystal can be experimentally determined by Bragg's equation,
nλ = 2dsinθ,
where λ is the wavelength of x-rays, d is the distance between atomic planes, θ is the angle of reflection (in degrees), and n is a positive integer.
Notice that Bragg's equation is a trigonometric function. By the end of this tutorial you should be able to work with this and other trigonometric functions when you encounter them in the classroom or laboratory.
In the next section we will explore the basics of trigonometric functions.