A triangle with an area of 136 square centimeters has a height that is 2 more than 4 times its base. Find the base and height, in centimeters, of the triangle.

1 answer

Let the base of the triangle be denoted as \( b \) cm. According to the problem, the height \( h \) of the triangle can be expressed in terms of the base as follows:

\[ h = 4b + 2 \]

The area \( A \) of a triangle is given by the formula:

\[ A = \frac{1}{2} \times \text{base} \times \text{height} \]

We are given that the area of the triangle is 136 square centimeters. Substituting for \( A \), \( b \), and \( h \):

\[ 136 = \frac{1}{2} \times b \times (4b + 2) \]

To eliminate the fraction, we multiply both sides by 2:

\[ 272 = b \times (4b + 2) \]

Next, we expand the right-hand side:

\[ 272 = 4b^2 + 2b \]

Rearranging this equation gives us a standard form quadratic equation:

\[ 4b^2 + 2b - 272 = 0 \]

To simplify, we can divide every term by 2:

\[ 2b^2 + b - 136 = 0 \]

Next, we will use the quadratic formula to solve for \( b \). The quadratic formula is given by:

\[ b = \frac{-B \pm \sqrt{B^2 - 4AC}}{2A} \]

Where \( A = 2 \), \( B = 1 \), and \( C = -136 \). First, we compute the discriminant:

\[ B^2 - 4AC = 1^2 - 4 \cdot 2 \cdot (-136) = 1 + 1088 = 1089 \]

Now we take the square root of 1089:

\[ \sqrt{1089} = 33 \]

Now we can substitute back into the quadratic formula:

\[ b = \frac{-1 \pm 33}{2 \cdot 2} = \frac{-1 \pm 33}{4} \]

Calculating the two potential values for \( b \):

  1. \( b = \frac{-1 + 33}{4} = \frac{32}{4} = 8 \)
  2. \( b = \frac{-1 - 33}{4} = \frac{-34}{4} = -8.5 \) (not a valid solution since the base cannot be negative)

Thus, the base of the triangle is:

\[ b = 8 \text{ cm} \]

Now that we have \( b \), we can find the height \( h \):

\[ h = 4b + 2 = 4(8) + 2 = 32 + 2 = 34 \text{ cm} \]

In conclusion, the dimensions of the triangle are:

\[ \text{Base} = 8 \text{ cm}, \quad \text{Height} = 34 \text{ cm} \]

Thus, the final answer is:

\[ \text{Base} = 8 \text{ cm}, \quad \text{Height} = 34 \text{ cm} \]