Calculate Parallelogram Side Length CD Given 45cm Perimeter and AB=15cm

To solve this problem, we will calculate side $CD$ using the perimeter formula of a parallelogram:

• The perimeter formula of a parallelogram is $P = 2 \times (AB + CD)$.
• Given $P = 45$ cm and $AB = 15$ cm, substitute these values into the equation: $45 = 2 \times (15 + CD)$.
• Simplify the expression: $45 = 30 + 2 \times CD$.
• Rearrange the equation to solve for $CD$: $2 \times CD = 45 - 30$.
• This simplifies to: $2 \times CD = 15$.
• Divide both sides by $2$ to find $CD$: $CD = \frac{15}{2}$.
• Thus, $CD = 7.5$ cm.

Therefore, the length of side $CD$ is $7.5$ cm.