Given: Circle A externally tangent to Circle B.
2 answers:
<h2>Answer:</h2>
B. 3
<h2>Step-by-step explanation:</h2>A tangent is a line that passes through exactly one point on a circle. For any point on a circle, the radius and tangent line through that point are always perpendicular to each other making a right angle. If two triangles touch each other externally, then there will be 3 lines making right angle with radius of the circles at the point of intersection of circle and tangents. These three tangent lines are shown below. They are the black, blue and green ones.
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Answer:
- m∠A ≈ 53.13°
- m∠B ≈ 73.74°
- m∠C ≈ 53.13°
Step-by-step explanation:
An altitude to AC bisects it and creates two congruent right triangles. This lets you find ∠A = ∠C = arccos(6/10) ≈ 53.13°.
Since the sum of angles of a triangle is 180°, ∠B is the supplement of twice this angle, so is about 73.74°.
m∠A = m∠C ≈ 53.13°
m∠B ≈ 73.74°
_____
The mnemonic SOH CAH TOA reminds you of the relation between the adjacent side, hypotenuse, and trig function of an angle:
Cos = Adjacent/Hypotenuse
If the altitude from B bisects AC at X, triangle AXB is a right triangle with side AX adjacent to the angle A, and side AB as the hypotenuse. AX is half of AC, so has length 12/2 = 6, telling you the cosine of angle A is AX/AB = 6/10.
A diagram does not have to be sophisticated to be useful.
