Here we have three triangles, and all of them are congruent. (so what's 4 units on one side is also 4 units on the sides of the other triangles)
The perimeter of CAT = CA + AT + CT (the sides of the triangle) We know that CA = 12 units, since it is labelled. We know that DG is 4 units, and since AO and TO must be the same length as DG, they are also 4 units. 4 + 4 = 8 units, the length of AT. We know that CG is 5 units. CG and GT are the same length. 5+5 = 10 = CT CAT = 12 + 8 + 10 = 30 units
Perimeter of DOG = DO + OG + DG DG = 4, it is labelled DO = 5 since it is the same length as CG We know that CA is 12 units, and it is made up of two equal parts, AD and CD. Therefore AD and CD = 6 units. (half of 12). OG is the same size. DOG = 4 + 5 + 6 = 15 units
