Question 1098677
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I guess that the circles are touching externally,

although the condition/your post does not state it.



Then one side of the triangle has the length of  5+7 = 12 cm;

the other side has the length of  5+8 = 13 cm

and the third side  has the length of  7+8 = 15 cm.


Then the perimeter of the triangle is  12 + 13 + 15 = 40 cm.


<U>Answer</U>.  The perimeter of the triangle ABC is 40 cm.
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