<h3>Given</h3>
... r + 7 = 9
<h3>Find</h3>
... r
<h3>Solution</h3>
Subtract 7 from both sides of the equation.
... r + 7 - 7 = 9 - 7
... r = 2 . . . . . . simplify
Expressed as a solution set, this may look like ...
... r ∈ {2}
_____
You probably had no trouble solving this in 2nd grade when it was shown to you in the form ...
__ + 7 = 9
It's right triangle 45 45 90
The sides in this triangle<span> are in the ratio 1 : 1 : 1√2
if one side = </span>2√2 then b = 2√2
hypo. a = b(√2) = 2(2√2) = 4√2
answer
a = 4√2
b = 2√2

where r is the radius of a circle.