Question is Incomplete, Complete question is given below.
Prove that a triangle with the sides (a − 1) cm, 2√a cm and (a + 1) cm is a right angled triangle.
Answer:
∆ABC is right angled triangle with right angle at B.
Step-by-step explanation:
Given : Triangle having sides (a - 1) cm, 2√a and (a + 1) cm.
We need to prove that triangle is the right angled triangle.
Let the triangle be denoted by Δ ABC with side as;
AB = (a - 1) cm
BC = (2√ a) cm
CA = (a + 1) cm
Hence,
Now We know that

So;


Now;

Also;

Now We know that




[By Pythagoras theorem]

Hence, 
Now In right angled triangle the sum of square of two sides of triangle is equal to square of the third side.
This proves that ∆ABC is right angled triangle with right angle at B.
Answer:
Option B: 3x + 3y - 3
Step-by-step explanation:
In an isosceles triangle, the two congruent sides are equal.
We are told the base is; x - y - 2 units
Now let each of the congruent sides be represented as A.
Thus the perimeter equation will be;
P = 2A + x - y - 2
Now, we are told that the perimeter is; 7x + 5y - 8 units
Thus;
7x + 5y - 8 = 2A + x - y - 2
Rearranging gives;
7x - x + 5y + y - 8 + 2 = 2A
2A = 6x + 6y - 6
Divide through by 2 to give;
A = 3x + 3y - 3 units
Answer:
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