Deltoid Geometry: Calculate CO Given AO=6cm, BO=5cm, and Area=80cm²

Question

Given ABCD deltoid AD=AB CB=CD

The diagonals of the deltoid intersect at the point O

Given in cm AO=6 BO=5

The area of the deltoid is equal to 80 cm².

Calculate the side CO

S=80S=80S=80666555DDDAAABBBCCCOOO

Video Solution

Solution Steps

00:15 Let's find the length of side C O.
00:19 We'll use the formula to calculate the area of a kite.
00:23 It's diagonal times diagonal, divided by 2.
00:29 The main diagonal intersects the secondary diagonal.
00:47 We'll substitute the value of B O to find B D.
00:57 Next, substitute B D into the kite area formula.
01:03 Multiply by 2 to get rid of the fraction.
01:09 Let's isolate A C.
01:12 This gives us the length of diagonal A C.
01:18 The side A C is the sum of A O and O C.
01:24 Now, plug in the side values to find O C.
01:29 And that's the solution to our problem!

Step-by-Step Solution

To solve for COCO, we will use the area formula for the deltoid:

  • Step 1: Calculate full length of diagonal BDBD:

BD=2×BO=2×5=10 cmBD = 2 \times BO = 2 \times 5 = 10 \text{ cm}.

  • Step 2: Use the kite area formula:

  • Area=12ACBD\text{Area} = \frac{1}{2} \cdot AC \cdot BD.

Substitute known values into the formula:

80=12(6+CO)1080 = \frac{1}{2} \cdot (6 + CO) \cdot 10.

Step 3: Simplify and solve for COCO:

80=5(6+CO)80 = 5 \cdot (6 + CO) leads to

80=30+5CO80 = 30 + 5CO.

Solving for COCO, we subtract 30 from both sides:

50=5CO 50 = 5CO ,

CO=505=10 CO = \frac{50}{5} = 10 .

Therefore, the side COCO is 10 cm.

Answer

10