For

and

, it's helpful to remember the half-angle identities:


So


For

, the Pythagorean identity suffices:

which means

since

.
Answer:
a length of a cd is 6 inches
Step-by-step explanation:
6/ sqrt(8)=
6/sqrt(8) * sqrt(8)/sqrt(8)
6sqrt(8)/8
3/4 * sqrt(8)
3/4 * sqrt(4*2)
3/4 * sqrt(4) * sqrt(2)
3/4 *2*sqrt(2)
3/2 *sqrt(2)
5/sqrt(11) *sqrt(11)/sqrt(11)
5sqrt(11)/11
5/11 *sqrt(11)