Answer/Step-by-step explanation:
1. <B is an inscribed angle in a circle which intercepts arc AC.
Therefore, m<B = ½ of m<AC
B = ½ * 128° = 64°
x = 180 - (64 + 43)
x = 180 - 107 = 73°
2. The circle given shows two chords intersecting at point H.
According to intersecting chords theorem, the products of the segments formed by one chord equals the product of the segments formed by the other.
Therefore,

Solve for x

Divide both sides by 10

<h3>
Answer: (ab - c)(ab + c)</h3>
===================================================
Work Shown:
a^2b^2 - c^2
(ab)^2 - c^2
(ab - c)(ab + c)
In the last step, I used the difference of squares factoring rule.
A perfect square is a number which contains a a factor that involves a number multiplied by itself. You could also say a perfect square, when taken the square root of such a number, involves a whole number answer. Either explanation would work, and there are surely mainly more haha. 25 is the perfect square because 5×5 is a factor of 25, while 50 doesn't have a factor of the same numbers.