spheer surfus area=2* area av hemispheer
hemispheer: make serkel rings round a vertikal axis
if yu start at top, radius av ring=r=R*sine(angel)
ring area=2*pi*r d(angel) or d(hite), weer hite=R*d(angel)
integrate from angel=0 tu 90 deg (pi/2)
become 2*pi* r^2 evaluated at r=0 & r=R
area av hemispheer=2pi R^2
area av spheer=4pi R^2
----or look at strip hite as R*kosine(angel) as angel go from 0 tu 90 deg
integral(kosine)=sine, evaluated at 0 & 90 deg...=1 at 1 end & zero at other end