Deduce la ecuación de la circunferencia con centro en el origen con el radio dado a)r=1

How do i multiply two digit numbers

Jake bakes and sell apple pies. he sells each pie for $5.75 . the materials to make the pies cost $40. the boxes jake puts the pies in cost & 12.50 total. how many pies does jake need to sell to earn a profit of $50

The area of a circle is equal to 1 dm². find the radius of the circle.