Answer:
a)
![√(64+x^2)](https://img.qammunity.org/2021/formulas/mathematics/high-school/kx2h0gh2m2et653iokxlogy3r5kvcjrziv.png)
b) 15
Explanation:
a) We know that AB = 8 and BC = x. We can use the Pythagorean Theorem, which states that for a right triangle with sides a, b, and c:
, where a and b are the shortest sides and c is the longest.
Here, AB = a = 8 and BC = b = x. So, AC = c. Then:
![AB^2+BC^2=AC^2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ktgd3nwz3h2fsjo499wi8aac1o4zpv341u.png)
![8^2+x^2=AC^2](https://img.qammunity.org/2021/formulas/mathematics/high-school/dpoqfm5ht16yc27xwgvgf1xhshomygdd96.png)
![AC=√(64+x^2)](https://img.qammunity.org/2021/formulas/mathematics/high-school/rc42zz4hr7muvd5dq6lkg0tjh0pjf0zlv7.png)
b) We know that AC - AB = 9. Since AB = 8, then AC = 9 + 8 = 17. We also have the expression from above, so set them equal:
![AC=√(64+x^2)=17](https://img.qammunity.org/2021/formulas/mathematics/high-school/460w1z3dxtoi2dtsoanu4vmm25m415iwv2.png)
![64+x^2=289](https://img.qammunity.org/2021/formulas/mathematics/high-school/mzigtr0gqncnrlupsatgmegfd8fc99z46i.png)
![x^2=225](https://img.qammunity.org/2021/formulas/mathematics/high-school/87qmtijbx5iy7eokxgld84md2hfzz73y6k.png)
x = 15
Hope this helps!