Answer:
a²-r²= 22
Explanation:
2π(a-r)(a+r)+4 = 52π
=> 2π(a²-r²)+4= 52π
=> (a²-r²)+4 = 52π/2π
=> (a²-r²)+4 = 26
=> (a²-r²)= 26-4
=> a²-r²= 22
2π(a-r)(a+r)+4 = 52
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