Πεψενθε 

c = 20, R = 10, a = 16 

`and`(b = sqrt(`+`(`^`(20, 2), `-`(`^`(16, 2)))), `and`(sqrt(`+`(`^`(20, 2), `-`(`^`(16, 2)))) = sqrt(`*`(4, 36)), sqrt(`*`(4, 36)) = 12)) 

`and`(r = `+`(`/`(`*`(16, `*`(`*`(`/`(1, 2), 12))), `*`(`*`(`/`(1, 2), `+`(`+`(20, 12), 16))))), `+`(`/`(`*`(16, `*`(`*`(`/`(1, 2), 12))), `*`(`*`(`/`(1, 2), `+`(`+`(20, 12), 16))))) = 4)