Let's rotate and redraw the figure to make it easier to understand:
The figure appears to be a right triangle with its hypotenuse and opposite side given.
Since this is a right triangle, to be able to get the measurement of the adjacent side, we will be using the Pythagorean Theorem:
![a^2+b^2=c^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/fdnnfwrccw5g60jmi691r5gcz9ekxf8waa.png)
The formula for the adjacent side or c is:
![a^2+b^2=c^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/fdnnfwrccw5g60jmi691r5gcz9ekxf8waa.png)
![b^2=c^2-a^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/5cw06zwjh1szoeepv4ywr3m2sldt68z3j0.png)
Let's now plug in the given values to get b.
![b^2=c^2-a^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/5cw06zwjh1szoeepv4ywr3m2sldt68z3j0.png)
Given: c² = 225 and a² = 145
![b^2=225\text{ - 145}](https://img.qammunity.org/2023/formulas/mathematics/college/i6k8dbv2eq33nvj43hudu1qr5y3ds6l51s.png)
![b^2=80](https://img.qammunity.org/2023/formulas/mathematics/college/jq5vn9xhbi2t1uo5iohsk47ak1kumhvurw.png)
![b\text{ = }\sqrt[]{80}\text{ = }\sqrt[]{16\text{ x 5}}\text{ = 4}\sqrt[]{5}](https://img.qammunity.org/2023/formulas/mathematics/college/2gf7gab2x5hp8sqqcrlz4rw6jagte3xkux.png)