Instructions: Find the missing side lengths. Leave your answers as radicals in the simplest form. I need help with finding what a is.

Answer:
a = 17
Step-by-step explanation:
using the cosine ratio in the right triangle and the exact value
cos45° = [tex]\frac{1}{\sqrt{2} }[/tex] , then
cos45° = [tex]\frac{adjacent}{hypotenuse}[/tex] = [tex]\frac{a}{17\sqrt{2} }[/tex] = [tex]\frac{1}{\sqrt{2} }[/tex] ( cross- multiply )
a × [tex]\sqrt{2}[/tex] = 17[tex]\sqrt{2}[/tex] ( divide both sides by [tex]\sqrt{2}[/tex] )
a = 17
b = 17 since the legs of an isosceles triangle are congruent