Question

Karen drew a triangle with side lengths 3 centimeters 4 centimeters and 5 Centimeters what is the perimeter of the triangle

Answer 1

you just need to add the sides

Answer 2

formula:
P△=s1+s2+s3

where P = perimeter of triangle
s1,s2,s3 are the three sides.

P△=3+4+5

P△=12 cm.