Math Problem Statement

Kyla makes a triangular school pennant. The area of the triangle is 180 square inches. The base of the pennant is z inches long. The height is 6 inches longer than twice the base length. What is the height of the pennant? Recall the formula A = bh. 12 inches 15 inches 30 inches 36 inches

Kyla makes a triangular school pennant. The area of the triangle is 180 square inches. The base of the pennant is z inches long. The height is 6 inches longer than twice the base length. What is the height of the pennant?

Solution

We are given a triangular pennant, with the following details:

  • The base is zz inches long.
  • The height is 2z+62z + 6 inches, which is 6 inches longer than twice the base.
  • The area AA of the triangle is 180 square inches.

We need to find the height.

Formula:

The area of a triangle is given by the formula: A=12×base×heightA = \frac{1}{2} \times \text{base} \times \text{height}

Substituting the given values:

180=12×z×(2z+6)180 = \frac{1}{2} \times z \times (2z + 6)

Solve for zz:

  1. Multiply both sides of the equation by 2 to eliminate the fraction: 360=z×(2z+6)360 = z \times (2z + 6)

  2. Distribute zz: 360=2z2+6z360 = 2z^2 + 6z

  3. Rearrange the equation into standard quadratic form: 2z2+6z360=02z^2 + 6z - 360 = 0

  4. Divide the entire equation by 2 to simplify: z2+3z180=0z^2 + 3z - 180 = 0

Solve the quadratic equation using the quadratic formula:

The quadratic formula is: z=b±b24ac2az = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} For the equation z2+3z180=0z^2 + 3z - 180 = 0, we have a=1a = 1, b=3b = 3, and c=180c = -180.

Now, let's calculate the value of zz.The solutions for zz are z=12z = 12 and z=15z = -15. Since the base of the triangle cannot be negative, we select z=12z = 12.

Find the height:

The height of the pennant is 2z+62z + 6, so: Height=2(12)+6=24+6=30 inches.\text{Height} = 2(12) + 6 = 24 + 6 = 30 \text{ inches}.

Thus, the height of the pennant is 30 inches.

Would you like more details on the process or have any questions?

Here are 5 related questions to expand on this problem:

  1. What is the perimeter of the triangular pennant if the third side is unknown?
  2. How would the area change if the base was increased by 5 inches?
  3. Can you verify the solution by plugging z=12z = 12 into the area formula again?
  4. How do we derive the quadratic formula from completing the square?
  5. What is the geometric significance of a negative solution in this context?

Tip: When solving quadratic equations, always verify if both solutions are feasible in the context of the problem.

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Math Problem Analysis

Mathematical Concepts

Geometry
Algebra
Quadratic Equations

Formulas

Area of a triangle: A = 1/2 * base * height
Quadratic equation formula: ax^2 + bx + c = 0

Theorems

Quadratic Formula

Suitable Grade Level

Grades 7-9