Math Problem Statement

The base of a triangle is four more than twice its height. If the area of the triangle is 53 square​ centimeters, find its base and height.

Solution

To solve this problem, we use the formula for the area of a triangle:

Area=12×base×height.\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}.

Step 1: Define Variables

Let the height of the triangle be hh cm.
The base is given as 2h+42h + 4 cm.
The area is 53 cm².

Step 2: Substitute into the Area Formula

53=12×(2h+4)×h.53 = \frac{1}{2} \times (2h + 4) \times h.

Step 3: Simplify the Equation

Multiply through by 2 to eliminate the fraction: 106=(2h+4)h.106 = (2h + 4)h.

Expand the right-hand side: 106=2h2+4h.106 = 2h^2 + 4h.

Step 4: Rearrange into Standard Quadratic Form

2h2+4h106=0.2h^2 + 4h - 106 = 0.

Divide through by 2 to simplify: h2+2h53=0.h^2 + 2h - 53 = 0.

Step 5: Solve the Quadratic Equation

We use the quadratic formula: h=b±b24ac2a.h = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}. Here, a=1a = 1, b=2b = 2, and c=53c = -53.

h=2±224(1)(53)2(1).h = \frac{-2 \pm \sqrt{2^2 - 4(1)(-53)}}{2(1)}.

Simplify under the square root: h=2±4+2122.h = \frac{-2 \pm \sqrt{4 + 212}}{2}. h=2±2162.h = \frac{-2 \pm \sqrt{216}}{2}. h=2±14.72.h = \frac{-2 \pm 14.7}{2}.

Step 6: Calculate the Two Solutions

  1. h=2+14.72=12.72=6.35h = \frac{-2 + 14.7}{2} = \frac{12.7}{2} = 6.35 cm.
  2. h=214.72=16.72=8.35h = \frac{-2 - 14.7}{2} = \frac{-16.7}{2} = -8.35 cm (not possible because height cannot be negative).

Thus, h=6.35h = 6.35 cm.

Step 7: Calculate the Base

Base=2h+4=2(6.35)+4=12.7+4=16.7cm.\text{Base} = 2h + 4 = 2(6.35) + 4 = 12.7 + 4 = 16.7 \, \text{cm}.

Final Answer:

  • Height: 6.35cm6.35 \, \text{cm}
  • Base: 16.7cm16.7 \, \text{cm}

Let me know if you would like more details about this solution.

Here are five related questions for further exploration:

  1. How do you derive the quadratic formula?
  2. What are the conditions for a quadratic equation to have real roots?
  3. Can you explain how to graph a quadratic equation like h2+2h53=0h^2 + 2h - 53 = 0?
  4. How does changing the base or height affect the area of a triangle?
  5. Could you calculate the dimensions of a triangle with an area of 100 cm², if the base is twice the height?

Tip: Always check the units in your problem to ensure consistency and correctness!

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Math Problem Analysis

Mathematical Concepts

Geometry
Algebra
Quadratic Equations

Formulas

Area of a triangle = 1/2 × base × height
Quadratic equation formula: x = (-b ± √(b² - 4ac)) / 2a

Theorems

Quadratic Formula

Suitable Grade Level

Grades 8-10