A perimeter of a triangle can be found using the following: 1) measurement of 3 sides are given: P = a + b + c 2) 2 sides of a right angle triangle is given: a² + b² = c² ; P = a + b + c 3) 2 sides of a triangle is given with the measurement of an angle. c² = a² + b² - 2ab(cos(C)).
Since, only the measurement of 2 sides is given, we can assume that the triangle is a right-angled triangle. c² = a² + b² c² = 20² + 15² c² = 400 + 225 c² = 625 c = √625 c = 25
