Understand how the formula is derived. Some math and physics formulas have mnemonic devices that have been around for a long time. Sometimes Math is Fun and sometimes it could be a surprising fact too.
You can use this as a go-to sheet whenever you want to prepare Class 9 Maths Formulas.
Circumference of the circle 2 p r. Math formula for class 9. Read over tomorrows math lesson today. Area of the circle p r 2.