#### Answer

b=8

#### Work Step by Step

Given that triangle is right angle triangle where a=15 and c=17
and b has to be found
formula for finding hypoteneus of right andle triangle is $a^{2}$+$b^{2}$=$c^{2}$
so after putting values of a and b,
$15^{2}$+$b^{2}$=$17^{2}$
225+$b^{2}$=289
$b^{2}$=64
b=$\sqrt 64$=8