You go on a trip to Italy and want to visit its famous land marks, your first stop in the leaning tower of Pisa. You see the 184.5 foot land mark casts a 123 ft shadow. You want to figure out how long it is from the top of the tower to the ground. Use cosine to figure out the length of line a.
SOH CAH TOA
You may think that this is a very pointless skill to master but actually people use this is their everyday life. For example, if you are a roofer you would need to know which ladder you would need to use to reach the roof.