Answer:
20
Explanation:
We can solve for the unknown base using Pythagorean's theorem.
Remember Pythagorean's theorem goes as such:
![a^2+b^2=c^2](https://img.qammunity.org/2023/formulas/mathematics/high-school/fdnnfwrccw5g60jmi691r5gcz9ekxf8waa.png)
Where a and b are the two legs and c is the hypotenuse. We know one leg and the hypotenuse so we can insert our known values and solve for the unknown.
![15^2+b^2=25^2\\225+b^2=625\\b^2=400\\b=20](https://img.qammunity.org/2023/formulas/mathematics/high-school/dnhk2hzhdrxi8wizw7n987l2dlo39gn59y.png)
Or using trigonometry:
Note this is a 45-45-90 triangle, therefore all angles are known.
I'll use the sin function with the B angle.
![sin(45)=(b)/(25) \\25*sin(45)=b\\17.67=b](https://img.qammunity.org/2023/formulas/mathematics/high-school/7ptbsoohqgro6arwarv591ti0uk3xm4q4a.png)
I'm assuming this problem was not made for trig, although the answer is still close.