We are given a circle with center O. CD is a tangent to the circle at point C. Angle CDB is given as $34^{\circ}$. We need to find the value of angle X, which is angle CAB.
2025/6/17
1. Problem Description
We are given a circle with center O. CD is a tangent to the circle at point C. Angle CDB is given as . We need to find the value of angle X, which is angle CAB.
2. Solution Steps
Let .
Since CD is a tangent to the circle at C, and subtend the same arc BC.
Therefore, .
Angle BCD and angle CDB and angle DBC sum to because they form the angles of a triangle.
Thus, .
.
Since O is the center of the circle, because the angle subtended by an arc at the center of the circle is twice the angle subtended by the same arc at any point on the remaining part of the circle.
Also, OC = OB (radii of the same circle). Therefore, is an isosceles triangle.
.
The angles in triangle OCB sum to , so .
.
.
.
.
Since CD is a tangent to the circle at C, .
.
.
.
In , .
.
Also, we know . So, .
We also know .
We have .
But we don't have enough information to calculate .
Using the alternate segment theorem, we have .
In triangle CDB, we have .
Thus, .
because CD is a tangent to the circle at point C.
.
because triangle OBC is an isosceles triangle with OB = OC.
(angle at the center is twice the angle at the circumference).
.
which gives no information.
We know . In triangle CDB, we have .
Therefore , so .
Now, consider triangle COB. OC = OB, so it's an isosceles triangle. Thus .
Since , then .
Also, CD is a tangent, so .
We have .
So , which doesn't help.
Using Tangent-Chord Theorem, we have . Also . In triangle , . Also, since , then , but it does not help to know more.
Consider the triangle CDB, . Since and , we have .
. OCB is isosceles so .
, but there is no connection between the angles.
Since
In triangle BCD,
So ,
Draw the radius OC. CD is tangent to C so .
Also OB = OC so is isosceles, so
In ,
Since , and (angle in a semi-circle) then and by the property of the circle is a tangent
Also . since the circle center is at , then , then
Then -> --> . Therefore DBC can be written as DBO+OBC
If , OBC = 90-56 = 34 degree which happens when is 0
The angle made by tangent to a circle with the chord drawn is the same as the angle in the alternate segment.
However, . No other conditions, therefore we can deduce which means and hence, .
3. Final Answer
56