The area of a triangle is given by:
Where
A is the area
b is the base length
h is the height
We can clearly see that the height, h, is 17.
The base of the flag would be:
34 - (10 + 7)
= 34 - (17)
= 17
b = 17
Now, we can simply substitute and find out the answer:
Answer
144.5 square centimeters