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1. The lengths of two sides of a triangle are 8cm and 12cm respectively. Find the perimeter of the triangle 2. The length of three sides of an isosceles triangle is 4cm, (3x-2) cm, (x / 2 + 1) cm respectively. Find the value of X and the length of three sides of the isosceles triangle 3. In triangle ABC, ∠ B is 15 ° smaller than ∠ a, and ∠ A is 15 ° smaller than 2 times of ∠ C. calculate the size of each internal angle —— Write the third question clearly, and it's better to solve three questions together
According to the first question, the sum of two sides is greater than the third side, and the difference of two sides is less than the third side. So the range of the third side is 4 to 20 (can't take etc.), so the perimeter range is 24 to 40
If 3x-2 = 4, then x = 2, so the other side is satisfied with 2! If x / 2 + 1 = 4, then x = 6, so the other side is not satisfied with 16
Let a = x, so B = X-15, C = (x + 15) / 2. According to the sum of the inner angles of a triangle, x = 75
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