Which equation can be used to find the unknown length, a, in this triangle?15 m17 m3+15² = 172152 +172 - a2² +15= 172at 15² = 17²

Answer:Here is the complete question.(attachment)The correct choice is [tex]a^2+15^2=17^2[/tex] Step-by-step explanation:We will apply the Pythagoras formula to calculate the perpendicular length (a).Pythagoras formula [tex]=(base)^2+(perpendicular)^2=(Hypotenuse)^2[/tex]The right angle is formed between [tex]a[/tex] and [tex]15\ m[/tex] length.So [tex]17\ m[/tex] is the hypotenuse opposite to right angle is the longest side and called the hypotenuse.So[tex](a)^2+(15)^2=17^2[/tex][tex]a=\sqrt{17^2-15^2}= 8\ m[/tex]So the measure of side length [tex]a[/tex] is [tex]8\ m[/tex].That can be calculated from the option A that is [tex](a)^2+(15)^2=17^2[/tex].Note:Please don't look to the marked answers that was wrong in the attachment.