 This video explains how to use your calculator to do inverses. You will want to watch the two calculator videos depending on which calculator you have. You do enter these problems differently. So take a look at those calculator videos before you watch this video and hopefully that will help answer any questions on how to enter this on your calculator. So we're going to find the measure of A for the following problems. Be sure that your calculator is in degree mode. So again you want to make sure that you have watched the calculator videos so that you know how to put your calculator in degree mode. I talked about in the last video that the inverse is written with these little negative 1 so cosine and tangent when they are inverses have the little negative 1 in the upper right hand corner. And if we're going to do a problem like number 7 where it says tan of A equals .2638 what we want to do is we want to think of that as the inverse tan of 0.2638 and that's exactly what you enter on your calculator. And depending on what kind of calculator you have you might enter the number first and then the function. Other calculators you enter the function first and then the number. So either way depending on the calculator you have we should get about 15.4 degrees. So we know that angle A is 14.8 degrees in number 7. In number 8 we are going to do the inverse sign of .3974 and that's going to give us the angle measure for A which in this case is 23.4 degrees. And you'll want to pay attention to the directions because usually it will tell you how to round your answers sometimes it will want the nearest tenths sometimes it will want the nearest whole number. So this would be 23.4 if it wanted the nearest degree we would just say 23 degrees. Let me move this up a little bit here so we can see a couple other examples 9 and 10. Cosine of angle A equals 11 over 15 so what we're going to do is on our calculator we are going to enter the inverse cosine and do 11 divided by 15. And that's going to give us the measure of angle A. So again it's important that you know how to use your calculator to get the correct angle measure here and once you enter it correctly you should get 42.8 degrees. So angle A would be about 43 degrees. And in number 10 we are going to do the inverse tan of 16 divided by 11 and so we should get the answer for angle A is 55.5 degrees.