Help me on this please! I can’t find out how to do it!

Area of a rectangle = length x width
14 x 7 = 98cm2
25squaredx7squared = 175 (Pythagoras)
Sroot of 175 = 13.23
13.23cm (length of triangle)
13.23x7= 92.61
92.61 divided by 2
Area of triangle = 46.3cm2