Ineed with how to solve this geometry question! ! desperately

A squared plus b squared equals c squared

Hello Spongebob :-)

To find the missing side, you have to write a proportion because the sides are proportional.

When an angle is bisected like this, you can write:
28/x = 12/(30 - x)

Cross multiplying will give you:
12x = 840 - 28x
40x = 840
x = 21

You could plug the 21 back in and you will see that the sides are proportional.

Good luck!