Greenhouse Arc

Yesterday, I was reading posts on Gab and came across this post: @DemsFearTruth: Anyone good with math? I’m good with things up to a point, but I’ve not had to figure this type of math since HS. Trying to figure out how to take a straight line and determine how tall it would be, if bent into an arch. For example, if the width is 20 feet, and the pvc pipe is 40 feet in length, when bent into shape to arc from side to side of what will be a greenhouse, how tall will it be?