Factorise ab-a-b+1 =?

Find the solutions for a triangle with a =16, c =12, and b = 63º

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?

The candy store is having a 30% off sale. emma is going to buy $7.50 worth of candy. how much will she pay after the discount