Area of Deltoid: Calculate Using 7 and 5 Unit Diagonals

To solve this problem, we need to calculate the area of the deltoid $ABCD$ using the given lengths of its diagonals. The formula for the area of a deltoid (kite) is:

$A = \frac{1}{2} \times d_1 \times d_2$

Where $d_1$ and $d_2$ are the lengths of the diagonals. From the diagram, we know:

• Diagonal $AC = 7$ cm
• Diagonal $BD = 5$ cm

Substituting these values into the formula, we have:

$A = \frac{1}{2} \times 7 \times 5$

Calculating this gives:

$A = \frac{1}{2} \times 35 = 17.5$

Therefore, the area of the deltoid $ABCD$ is $17.5$ cm².

The correct answer from the given choices is:

$17.5$ cm².