well if a triangle is 400 square inches that mean the area is 400 and we know that the formula for area of a triangle is 1/2bh. we can do 400 = 10h/2 and now we solve for h. so times by 2 to get 800 = 10h and divide by 10 to get 80 inches. now substitute 80 in the equation and you get 400. so the answer is true.
for the second one the area of a trapezoid is (b_1+b_2)/2 • h so we substitute again to get 342 = 38h/2. now we can times by 2 to get 684 and divide by 38 to get 18. or you can do 19h = 342 and get 18.
now if you substitute the 18 in the equation you end up with 342. so the answer is true
