Question

can someone explain the proses of solving this? I don't need the answer but a step-by-step explanation would be super helpful!

Answer 1

Part 1

Focus on triangle ABC.

Since AB is a diameter of the circle, this means angle ACB is 90 degrees. Refer to Thale's Theorem. Or you could use the inscribed angle theorem. Thale's theorem is a special case of the inscribed angle theorem.

Minor arc CB is 48 degrees. Use the inscribed angle theorem to see that angle CAB is 48/2 = 24 degrees.

Therefore, angle CBA = 90 - (angle CAB) = 90 - 24 = 66 degrees

Answer: 66

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Part 2

Inscribed angle CBA was found to be 66 degrees back in part 1.

This doubles to 132 degrees to represent minor arc AC.

Or you could note that:

minor arc AC = 180 - (minor arc CB) = 180 - 48 = 132

Inscribed angle BCD is 48 degrees. This doubles to 96 degrees when using the inscribed angle theorem, and this is the measure of minor arc CBD.

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Here's what we know about the arc measures of the circle

• minor arc AC = 132 degrees
• minor arc CB = 48 degrees
• minor arc BD = 96 degrees

These three arcs, along with minor arc AD, will add up to get a full 360 degree circle. Check out the diagram below.

Adding those 3 pieces gets us 132+48+96 = 276

This means minor arc AD has to be 360 - 276 = 84 degrees

Then use the inscribed angle theorem one more time to divide the minor arc AD in half to get the inscribed angle ACD

84/2 = 42

Answer:  42