Surface Area of Spheres (1 of 2: Finding the Surface area of spheres and hemispheres)

About

I teach mathematics at a comprehensive public high school in Sydney, Australia. I'm also an author (Woo's Wonderful World of Maths, It's a Numberful World, Eddie Woo's Magical Maths 1 & 2, Whodunnit Eddie Woo?) and TV host (Ultimate Classroom on Channel 10, Teenage Boss on ABC ME). I think learning is awesome, and love being able to share what I've learned with others! More information about me and my work here: http://misterwootube.com/about/