Answer:
The area of the triangle is 28 square units
Explanation:
First we have to calculate the length of the base of the triangle and the length of the height
To calculate the base we have to subtract point (-1 , 2) from point (7 , 2)
(7 , 2) - (-1 , 2) = ((7 - (-1)) , (2 - 2)) = (8 , 0)
because it has no component in y this means that the length of the base is 8
b = 8
To calculate the height we have to subtract point (-1 , 2) from point (-1 , 9)
(-1 , 9) - (-1 , 2) = (((-1) - (-1)) , (9 - 2)) = (0 , 7)
because it has no component in x this means that the length of the base is 7
h = 7
To calculate the area of a triangle we have to multiply the base by the height and then divide it by 2
a = (b * h)/2
a = (8 * 7)/2
a = 56/2
a = 28
The area of the triangle is 28 square units