Answer:
a = 18.8
Step-by-step explanation:
With it being a right angle, you can use the pythagorean theorem equation.
[tex]a^{2} + b^{2} =c^{2} \\a^{2} + 18^{2} =26^{2} \\a^{2} +324 = 676\\a^{2} = 676 - 324 \\a^{2} = 352\\a = \sqrt{352} \\a = 18.76 = 18.8[/tex]
