A right isosceles triangle is drawn on a coordinate plane with the right angle vertex at (4,2) and another vertex at (8,2). Using the coordinates given, what is thr perimeter of the triangle? Round the answer to the nearest tenths place.

13.7 units
16.7 units
8.6 units
9.7 units

1 answer

To determine the perimeter of the right isosceles triangle with vertices at (4,2) and (8,2), let's identify the three vertices.

  1. Identifying the vertices:

    • The right angle vertex is at (4, 2).
    • One vertex (which we'll call \( B \)) is at (8, 2).
    • Since this is a right isosceles triangle, the two legs must be equal, and they are both perpendicular to each other.
  2. Calculating the length of the base (horizontal leg):

    • The distance from the point (4, 2) to (8, 2) is: \[ \text{Length of } AB = 8 - 4 = 4 \]
  3. Calculating the coordinates of the third vertex \( C \):

    • Since the triangle is isosceles, the height from vertex \( A \) (4, 2) to point \( C \) must also be 4 units long (the same as the length of leg \( AB \)).
    • The vertical leg would go either upwards or downwards from point \( A \). We can compute the coordinates for both scenarios, but it doesn't alter the length since both would give the same distance. Here, we take the vertex upward: \[ C = (4, 2 + 4) = (4, 6) \]
    • So the three vertices of the triangle are \( A(4,2) \), \( B(8,2) \), and \( C(4,6) \).
  4. Calculating the lengths of the other sides:

    • Length \( AC \) (from \( A(4, 2) \) to \( C(4, 6) \)): \[ AC = 6 - 2 = 4 \]
    • Length \( BC \) (from \( B(8, 2) \) to \( C(4, 6) \)):
      • To find this length, use the distance formula: \[ BC = \sqrt{(8 - 4)^2 + (2 - 6)^2} = \sqrt{4^2 + (-4)^2} = \sqrt{16 + 16} = \sqrt{32} = 4\sqrt{2} \]
  5. Perimeter of the triangle:

    • The perimeter \( P \) is the sum of all sides: \[ P = AB + AC + BC = 4 + 4 + 4\sqrt{2} \]
  6. Calculating \( 4\sqrt{2} \):

    • Approximating \( \sqrt{2} \) to about 1.414: \[ 4\sqrt{2} \approx 4 \times 1.414 \approx 5.656 \]
  7. Final perimeter computation:

    • Adding it up: \[ P \approx 4 + 4 + 5.656 = 13.656 \]
    • Rounding to the nearest tenths gives \( 13.7 \).

Thus, the perimeter of the triangle is 13.7 units.