Don't report this is serious 400 times 400 is 800 so what's 800 times 800

Find the length of the following tangent segments to the circles centered at o and o' whose radii are 5 and 3 respectively and the distance between o and o' is 12. what is the tangent segment of cd?

Need this asap if anyone can i would be very grateful. if you could show workings that would really

How do you write something in scientific notation?