The isosceles triangle theorem states that if two sides of a triangle are congruent, then the angles opposite those sides are

option (b) is correct

step-by-step explanation:

to find the solution of this system, we need to convert it into reduced row-echelon form. we have,

after applying row operations r2 -> r2/2 and r3 -> r3/3, we get,

a+b=c is your answer

the answer to your question might be 45 degrees.

90+45=135

180-135=45