Find the area explain confused on these

This is similar to the question before. Remember that the height of a triangle is drawn 90 degrees from the base (see the little square), meaning that the height is 6.9 cm.  And the base is the line the triangle is standing on ( which is 8.4 cm) 
 
Then put them into your formula  base x height / 2 

6.9 x 8.4 / 2 = 28.98 cm squared

For the first question the answer is a, for the second c, for the third d, for the 4th b, for the 5th a