Answer:
b =22
Step-by-step explanation:
The formula to calculate the area of a trapezoid:
1/2*(a+b)*h : (a: base, b: base, h: height)
The formula to calculate the area of a triangle:
1/2*a*h (a: base, h: height)
All inputs are given for trapezoid so let's first find the area of trapezoid then we can find the value of b:
1/2*(10+12)*7 = 77 cm^2 is the area of trapezoid
now for the area of triangle:
1/2*b*7 = 77 (it was given that the areas are equal)
first we multiply both sides by 2
7*b = 154 now divide both sides by 7
b = 22
