Find the circumference of a circle whose radius is 2/5m​

Anne is twice as old as bill, and bill is 3 years older than christie. the sum of anne s and christie s ages equal 72. find their age difference.?

Of four points are collinear, they are also coplanar

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)