Q7 of 67 Page 168

Suppose x2 + y2 = z2.

(i) if x = 4 and y = 3, find z;


(ii) if x = 5 and z = 13, find y;


(iii) if y = 15 and z = 17, find x.

(i) Given that x2 + y2 = z2


where x = 4 and y = 3


⇒ z2= 42 + 32


⇒ z2 = 16 + 9


⇒ z2 = 25


⇒ z = ±5


(ii) Given that x2 + y2 = z2


where x = 5 and z = 13


⇒ y2= 132 - 52


⇒ y2 = 169 - 25


⇒ y2 = 144


⇒ y = ±12


(iii) Given that x2 + y2 = z2


where y = 15 and z = 17


⇒x2= 172 - 152


⇒x2 = 289 - 225


⇒x2 = 64


⇒ x = ±8


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