We have to solve for the long diagonal.
Upper half of long diagonal^2 = 10^2 -8^2
Upper half of long diagonal^2 =100 -64
Upper half of long diagonal^2 =36
Upper half of long diagonal = 6
Lower Half of long diagonal^2 = 17^2 -8^2
Lower Half of long diagonal^2 = 289 -64
Lower Half of long diagonal^2 = 225
Lower Half of long diagonal = 15
Long Diagonal = 6 + 15 = 21 inches
Radical 64 is the same as saying the sqrt(64)
The answer is 8
From Pythagorean Identities <span><span><span>sin^2</span>x</span>+<span><span>cos^2</span>x</span>=1</span>
and from that identities we can have <span><span>sinx</span>+<span>cosx</span>=1</span>, taking <span><span>sinx</span>=1−<span>cosx</span></span> and substitute in the equation
<span><span>sinx</span>+<span>cosx</span>=1</span>
<span><span>(1−<span>cosx</span>)</span>+<span>cosx</span>=1</span>
Remove the parenthesis
<span>1−<span>cosx</span>+<span>cosx</span>=1</span>
cancel <span>cosx</span>
<span>1=1</span>
You just cross multiply and then simplify