The equation for area of a triangle is 0.5*base*height, so when you halve both the base and height, the area gets divided by 4.
The area of the first triangle is 0.5*80*40 = 1600 cm^2.
6 1/4 cm^2 is the same as 25/4 cm^2.
Now, we have to see how many times 1600 cm^2 can be divided by 4 to get 25/4 cm^2.
Area of second triangle: 1600/4 = 400
Area of third triangle: 400/4 = 100
Area of fourth triangle: 100/4 = 25
Area of fifth triangle = 25/4
So, the fifth triangle has an area of 6 1/4 cm^2.
The pattern would be the area of the nth triangle = [tex]\frac{1600}{4^{n-1}}[/tex]
