If △CDE has sides that are tangent to the circle, and CF=15 cm , BD=12 cm , and EG=4 cm , then what is the perimeter of △CDE ? (1 point)

1 answer

To find the perimeter of triangle \( \triangle CDE \) when the lengths \( CF \), \( BD \), and \( EG \) are given as tangent segments from points \( C \), \( D \), and \( E \) to the incircle of the triangle, we'll use the properties of tangent segments.

Given:

  • \( CF = 15 \) cm (let’s denote this length as \( a \)),
  • \( BD = 12 \) cm (we denote this as \( b \)),
  • \( EG = 4 \) cm (denote this as \( c \)).

In a tangent segment, the length from a point outside the circle to the point of tangency is equal for both tangents drawn from that point. Therefore, we can set the following:

  • Let \( CE = CF = a = 15 \) cm,
  • Let \( CD = BD = b = 12 \) cm,
  • Let \( DE = EG = c = 4 \) cm.

Now, the sides of triangle \( CDE \) can be represented in terms of the lengths of the tangent segments:

  • Side \( CD = CE = a = 15 \) cm,
  • Side \( DE = EG + GD = c + b = 4 + 12 = 16 \) cm,
  • Side \( CE = CF + FE = a + c = 15 + 4 = 19 \) cm.

To compute the perimeter \( P \) of triangle \( CDE \): \[ P = CD + DE + CE = 15 + 16 + 19 \] Calculating this: \[ P = 15 + 16 + 19 = 50 \text{ cm}. \]

Therefore, the perimeter of triangle \( \triangle CDE \) is \( \boxed{50} \) cm.