Answer:
The rectangle that we could use to find the area of the yellow triangle, is a rectangle of length = 12cm and a width = 8 cm. (A image of this can be seen below).
Remember that:
The area of a rectangle of length L and width W is:
A = W*L
The area of a triangle rectangle with catheti a and b is:
A = a*b/2
Then the area of the rectangle of length = 12cm and width = 8cm is:
A = 12cm*8cm = 96 cm^2
Now we need to subtract twice the area of a triangle rectangle of catheti a = 8cm and b = 6cm
(one cathetus is 6cm because is exactly half of the length of the rectangle)
The area of each one of these triangle rectangles is:
A' = 8cm*6cm/2 = 24cm^2
The area of the yellow triangle will be:
A = A - A' = 96cm^2 - 2*24cm^2 = 48cm^2
