Answer:
a=10
Explanation:
Using Pythagoras theorem
![{(a + 2)}^(2) + {( a- 5)}^(2) = {(a + 3)}^(2)](https://img.qammunity.org/2023/formulas/mathematics/college/yoetm8g0p14r53zwogzasgtgjirs5a9mvn.png)
![{a}^(2) + 4a + 4 + {a}^(2) - 10a + 25 = {a}^(2) + 6a + 9](https://img.qammunity.org/2023/formulas/mathematics/college/78oi4yh5etyk0xb9ubxg1ftrt8vjpn2tnk.png)
simplify:
![{a}^(2) - 12a + 20 = 0](https://img.qammunity.org/2023/formulas/mathematics/college/2gc6810wqfb0utfouv1vfcgwbauerks1qh.png)
(a-2)(a-10)=0
hence a= 2 or a=10 however we must reject 2 as the lengths of the triangle cannot be negative eg. the side for a-5 will be equivalent to -3 cm which is not possible for lengths to become negative