So I will be giving you the formula

This 
 is the hypothenuse which is opposite to 90 degrees
 is the hypothenuse which is opposite to 90 degrees
ill start from B
so 
 and
 and 
 can be any side except the side opposite to 90 degrees it shouldn't change.
 can be any side except the side opposite to 90 degrees it shouldn't change.
Answer for B with steps:
=> 

=>simplify 

=> get square root using your calculator 
 
 
=>the answer to B is 17.0 which is just 17 
Answer for C
=>

=>

=> subtract 49 on both sides 95 so its 

=> take square root 

=> Its 9.7
For the rest of the hard questions you have to know whats width is and height and the properties of rectangles they are very easy
As long as you understand the concept- 
follow the steps I provided.