A triangle's height is [tex]6c[/tex] meters and the base is [tex]c-1[/tex] meters. Brian knows that the area of the triangle is 18 square meters and is trying to find the height. Which shows the equation Brian can use and the correct measure of the height of the triangle?

Area of a triangle [tex]= 0.5 \times \text{base} \times \text{height}[/tex]

A. [tex]0.5(c-1)(6c) = 18;[/tex] height [tex]= 3[/tex] meters
B. [tex]0.5(c-1)(6c) = 18;[/tex] height [tex]= 18[/tex] meters
C. [tex](c-1)(6c) = 18;[/tex] height [tex]= 3[/tex] meters
D. [tex](c-1)(6c) = 18;[/tex] height [tex]= 18[/tex] meters



Answer :

Let's solve this step-by-step to find the correct equation and the measure of the height of the triangle.

Given:
- Height of the triangle [tex]\( h \)[/tex] is [tex]\( 6c \)[/tex] meters.
- Base of the triangle [tex]\( b \)[/tex] is [tex]\( c-1 \)[/tex] meters.
- Area of the triangle is 18 square meters.

The formula for the area of a triangle is:
[tex]\[ \text{Area} = 0.5 \times \text{base} \times \text{height} \][/tex]

Substitute the given values into the formula:
[tex]\[ 0.5 \times (c-1) \times (6c) = 18 \][/tex]

Let's simplify this equation step-by-step.

1. Multiply the constants and the variable expressions inside the equation:
[tex]\[ 0.5 \times 6c = 3c \][/tex]
So,
[tex]\[ 3c \times (c-1) = 18 \][/tex]

2. Distribute [tex]\( 3c \)[/tex] across [tex]\( (c-1) \)[/tex]:
[tex]\[ 3c^2 - 3c = 18 \][/tex]

3. Move all terms to one side to form a standard quadratic equation:
[tex]\[ 3c^2 - 3c - 18 = 0 \][/tex]

Now, we need to find the positive solution for [tex]\( c \)[/tex] since the length can't be negative. Solving the quadratic equation [tex]\( 3c^2 - 3c - 18 = 0 \)[/tex], we find:
[tex]\[ c = 3 \][/tex]

Next, we find the height of the triangle:
[tex]\[ \text{Height} = 6 \times c \][/tex]
[tex]\[ \text{Height} = 6 \times 3 \][/tex]
[tex]\[ \text{Height} = 18 \][/tex]

Thus, the correct measure of the height of the triangle is 18 meters, and the equation used to solve the problem is:
[tex]\[ 0.5 \times (c-1) \times (6c) = 18 \][/tex]

Therefore, the correct statement is:
[tex]\[ 0.5(c-1)(6 c)=18 ; \text{height } = 18 \text{ meters} \][/tex]