Calculate the area of triangle ABC with altitude CD, given A(−7, −1), B(−1, 5), C(0, 0), and D(−3, 3). 9 square units 18 square units 18.5 square units 21 square units

9514 1404 393

  18 square units

Step-by-step explanation:

Referring to the figure, we see that the base AB has a slope of 1, and the altitude CD has a slope of -1. The number of unit squares crossed by these segments are, respectively 6 and 3, so the length of each is ...

  AB = 6√2

  CD =3√2

The area is half the product of the base (AB) and height (CD) so is ...

  A = 1/2bh = (1/2)(6√2)(3√2) = 18

The area of ΔABC is 18 square units.

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Additional comment

It is useful to remember that the diagonal of a unit square is √2. We used that fact here. If you need to figure it using the Pythagorean theorem, you find ...

  c² = a² +b²

  c = 1² +1² = 2

  c = √2

y = 5x + 17

step-by-step explanation:

a perpendicular line will be the opposite reciprocal slope of the given equation.   the slope given is -1/5 so the opposite reciprocal is 5

find b:

7 = 5 (-2) + b

7 = -10 + b

17 = b

write equation

y = 5x + 17

c

step-by-step explanation:

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