Answer:
The third side of the triangle is (7a + 2b -1).
Step-by-step explanation:
The length of the first side = (3a +8)
The length of the second side = (5 +b)
Let us assume the third side = m
The perimeter of the triangle = SUM OF ALL 3 SIDES
⇒ (10a + 3b +12) = (3a +8) + (5 +b) + m
or, (10a + 3b +12) = 3a + b + 13 + m
or, m = (10a + 3b +12) -(3a + b + 13)
= 10 a + 3b + 12 - 3a - b - 13
= 7a + 2b -1 = ( 10 - 3a) + (3b -b) + 12 -13
or, m = (7a + 2b -1)
Hence, the third side of the triangle is (7a + 2b -1).
