Answer:
A
Explanation:
We need to use some properties of an isosceles triangle and the Pythagorean Theorem.
First, the vertical line down the middle of the triangle is the height, which means the angle is makes with the base is 90 degrees and it bisects the base. So, we have two right triangles, each with a height of 6 and with a base of 4/2 = 2.
We can now use the Pythagorean Theorem, which states that for a right triangle with legs a and b and hypotenuse c:
a² + b² = c²
Here, a = 6 and b = 2 and x = c, so:
a² + b² = c²
6² + 2² = x²
x² = 36 + 4 = 40
x = √40
Thus, the answer is A.