The problem asks to find the value of $x$ in each of the three figures, given that the segments that appear to be tangent are indeed tangent.

GeometryCirclesTangentsAnglesTrianglesQuadrilaterals
2025/5/13

1. Problem Description

The problem asks to find the value of xx in each of the three figures, given that the segments that appear to be tangent are indeed tangent.

2. Solution Steps

Figure 1:
The line is tangent to the circle at point A. Therefore, the radius OA is perpendicular to the tangent line at A. This means the angle OAB is a right angle, so it measures 9090^\circ. The triangle OAB is a right triangle.
The angle at O is 4040^\circ as shown in the figure. The sum of angles in triangle OAB is 180180^\circ.
So, 40+90+x=18040^\circ + 90^\circ + x = 180^\circ.
Therefore x=1809040=50x = 180^\circ - 90^\circ - 40^\circ = 50^\circ.
Figure 2:
The two tangent segments from the same external point to a circle are congruent.
Also, the two segments from the center to the points of tangency are radii, so they are congruent. The two segments form a quadrilateral.
The angles formed by radii and the tangents are right angles, each equal to 9090^\circ. The tangents form an angle of 3333^\circ.
The sum of the interior angles of the quadrilateral is 360360^\circ.
So 90+90+33+x=36090^\circ + 90^\circ + 33^\circ + x = 360^\circ.
Therefore x=360909033=147x = 360^\circ - 90^\circ - 90^\circ - 33^\circ = 147^\circ.
Figure 3:
Two tangent segments are drawn from the same external point to a circle. The two segments from the same external point to the circle are congruent. So the triangle formed by the two tangent segments and the line segment connecting the tangent points on the circle is an isosceles triangle. Let the angle at the center be xx^\circ. Since the lines connecting the center to the tangent points are perpendicular to the tangent lines, and the angle formed by the tangent lines is 4040^\circ, we have two right angles and an angle of 4040^\circ in a quadrilateral. Let the two angles in the isosceles triangle at the base be yy^\circ.
Then, we have 2y+40=1802y^\circ + 40^\circ = 180^\circ. Thus, 2y=1402y^\circ = 140^\circ, and y=70y^\circ = 70^\circ.
The lines connecting the center of the circle to the tangent point bisect the angle between the radii and the point where the tangent lines meet. The angle between the two radii is xx^\circ.
Consider the quadrilateral. We have two right angles at the intersection of the radii and tangent segments, so the sum of the central angle xx^\circ and the 4040^\circ tangent angle is 180180^\circ.
Thus, x+40=180x^\circ + 40^\circ = 180^\circ, which is incorrect.
The angle between the tangents is 40 degrees. Draw the segment from the center to the point where the tangent lines meet. This bisects the 40 degree angle, making it 20 degrees. Draw the radius to each tangent point. This is a right angle. Then consider the triangle formed by one of the tangent lines, the segment from the center to the tangent point, and the line from the center to where the tangent lines meet. This is a right triangle. The angle at the center is 90-20 = 70 degrees. The full angle at the center, xx is twice this, so x=270=140x = 2 * 70 = 140.

3. Final Answer

Figure 1: x=50x = 50
Figure 2: x=147x = 147
Figure 3: x=140x = 140

Related problems in "Geometry"

The problem states that the area of triangle OFC is $33 \text{ cm}^2$. We need to find the area of t...

AreaTrianglesSimilar TrianglesRatio and Proportion
2025/6/6

We are asked to calculate the volume of a cylinder. The diameter of the circular base is $8$ cm, and...

VolumeCylinderRadiusDiameterPiUnits of Measurement
2025/6/5

The problem asks us to construct an equilateral triangle with a side length of 7 cm using a compass ...

Geometric ConstructionEquilateral TriangleCompass and Straightedge
2025/6/4

The problem asks to construct an equilateral triangle using a pair of compass and a pencil, given a ...

Geometric ConstructionEquilateral TriangleCompass and Straightedge
2025/6/4

The problem asks to find the value of $p$ in a triangle with angles $4p$, $6p$, and $2p$.

TriangleAnglesAngle Sum PropertyLinear Equations
2025/6/4

The angles of a triangle are given as $2p$, $4p$, and $6p$ (in degrees). We need to find the value o...

TrianglesAngle Sum PropertyLinear Equations
2025/6/4

The problem asks to construct an equilateral triangle with sides of length 7 cm using a compass and ...

ConstructionEquilateral TriangleCompass and Straightedge
2025/6/4

We are given two polygons, $P$ and $Q$, on a triangular grid. We need to find all sequences of trans...

TransformationsRotationsReflectionsTranslationsGeometric TransformationsPolygons
2025/6/4

We need to describe the domain of the following two functions geometrically: 27. $f(x, y, z) = \sqrt...

3D GeometryDomainSphereHyperboloidMultivariable Calculus
2025/6/3

We need to find the gradient of the line passing through the points $P(2, -3)$ and $Q(5, 3)$.

Coordinate GeometryGradientSlope of a Line
2025/6/3