This is College Physics Answers with Shaun Dychko. We want to know the angle to the third order of maximum in Young's double slit experiment with slits that are separated with 0.1 millimeters with a monochromatic light of wavelength 580 nanometers. So, we have this formula for the maxima where <i>M</i> is some integer. It could be zero, negative one, one, negative two, and two, and so on. And, we're going to choose three. It's the third order maximum we're concerned with. And, we'll solve this for <i>Theta</i>, first of all, by dividing both sides by the separation between the slits <i>D</i> and then take the inverse sine of both sides, and we have the angle then is the inverse sine of the order times the wavelength divided by the slit separation. So, it's inverse sine of three times 580 times ten to the minus nine meters divided by 0.100 times ten to the minus three meters, giving us 0.997 degrees is the angle to the third order maximum.