<h3>
Answer: t = 43</h3>
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Explanation:
Inscribed angle ADB subtends the minor arc AB. Inscribed angle ACB subtends the same minor arc AB. The rule is that if two inscribed angles subtend the same arc, then they are the same measure.
We can prove this with the inscribed angle theorem which says
central angle = 2*(inscribed angle)
Let's say point E is the center of the circle. By the inscribed angle theorem, we know that,
angle AEB = 2*(angle ADB)
angle AEB = 2*43
angle AEB = 86
Then we go in reverse of this process to find angle ACB
angle AEB = 2*(angle ACB)
86 = 2*(angle ACB)
2*(angle ACB) = 86
angle ACB = 86/2
angle ACB = 43
So this is how we prove the two inscribed angles are congruent.