An isosceles triangle has two sides that are equal. ∆ABC has two equal sides. Thus, the angles opposite the two sides of an isosceles triangle are also congruent to each other.
X=5. Explanation: Take 3x+1=5x-9 and subtract 1 from both sides. Now you have 3x=5x-10, Subtract 5x from both sides to get -2x= -10 Now divide both sides by -2 and you have x=5 :).
