Deltoid Area Problem: Finding AC Length Given Area of 49 cm²

Question

Given the deltoid ABCD

Side length BD equals 7 cm

The area of the deltoid is equal to 49 cm².

Find the length of the side AC

S=49S=49S=49777AAABBBCCCDDD

Video Solution

Solution Steps

00:00 Find AC
00:03 We'll use the formula for calculating the area of a kite
00:07 (diagonal times diagonal) divided by 2
00:11 We'll substitute appropriate values according to the given data and solve for AC
00:22 We'll isolate AC
00:44 And this is the solution to the question

Step-by-Step Solution

To solve for the length of side AC in the deltoid:

  • Step 1: Identify the formula for the area, which is given by:
    Area=12×BD×AC \text{Area} = \frac{1}{2} \times BD \times AC where BDBD and ACAC are the diagonals.
  • Step 2: Substitute known values into the formula:
    Given that BD=7cmBD = 7\, \text{cm} and Area=49cm2\text{Area} = 49\, \text{cm}^2, we have:
    49=12×7×AC 49 = \frac{1}{2} \times 7 \times AC
  • Step 3: Solve the equation for ACAC:
    Multiply both sides of the equation by 2 to eliminate the fraction:
    98=7×AC 98 = 7 \times AC Divide both sides by 7:
    AC=987=14 AC = \frac{98}{7} = 14

Therefore, the length of the side ACAC is 14cm 14 \, \text{cm} .

Answer

14 14 cm