Deltoid Geometry: Finding Side Length AC Given Area 60cm² and BD=15cm

Question

Below is the deltoid ABCD.

Side length BD equals 15 cm.

The area of the deltoid is 60 cm².

Find the length of the side AC.

S=60S=60S=60151515AAABBBCCCDDD

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
00:12 We'll substitute appropriate values according to the given data and solve for AC
00:20 We'll isolate AC
00:36 We'll divide 60 by 15
00:42 And this is the solution to the question

Step-by-Step Solution

To solve this problem, we'll apply the following steps:

  • Step 1: Identify the given information: BD=15BD = 15 cm and the area is 6060 cm².

  • Step 2: Use the formula for the area of a deltoid.

  • Step 3: Solve for the unknown diagonal ACAC.

Now, let's work through each step:
Step 1: We know the area formula for a deltoid is given by: Area=12×AC×BD \text{Area} = \frac{1}{2} \times AC \times BD

Step 2: Substitute the given values into the formula: 60=12×AC×15 60 = \frac{1}{2} \times AC \times 15

Step 3: Simplify and solve for ACAC: 60=152×AC 60 = \frac{15}{2} \times AC
Multiply both sides by 2 to isolate ACAC: 120=15×AC 120 = 15 \times AC
Divide both sides by 15: AC=12015=8 AC = \frac{120}{15} = 8

Therefore, the length of the side ACAC is 8 8 cm.

Answer

8 8 cm