Answer:
10.28425
Step-by-step explanation:
 
        
             
        
        
        
3333334444444353553535354
        
             
        
        
        
Yes D is the correct option ! 
if you want to know how , comment, or you are good to go !
        
                    
             
        
        
        
First use Pythagoras theorem to find the remaining length of the base.
Then multiply the base with the altitude and divide that by 2 and you'll get the area