The diagram below shows circle LMNP with KL a tangent to the circle at L - NSC Technical Mathematics - Question 8 - 2021 - Paper 2
Question 8
The diagram below shows circle LMNP with KL a tangent to the circle at L.
LN and NPK arc straight lines.
∠N₁ = 27° and ∠M = 98°
8.1 Determine, giving reasons, whe... show full transcript
Worked Solution & Example Answer:The diagram below shows circle LMNP with KL a tangent to the circle at L - NSC Technical Mathematics - Question 8 - 2021 - Paper 2
Step 1
Determine, giving reasons, whether line LN is a diameter.
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Answer
To determine if line LN is a diameter, we can use the property that a diameter subtends a right angle to any point on the circumference of the circle.
Given that ∠M = 98°, we find that the opposite angle ∠N₁ = 27° does not satisfy the condition (
∠N₁ + ∠M = 125° which is not equal to 90°). Thus, line LN is not a diameter.
Step 2
Determine, stating reasons, the size of ∠P₂.
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Answer
The angle ∠P₂ is subtended by arc KL on the opposite side of the circle. According to the Inscribed Angle Theorem, the measure of an inscribed angle is half the measure of the arc it subtends.
Since ∠M = 98°,
ext∠P2=180°−∠M=180°−98°=82°.
Thus, ∠P₂ = 82°.
Step 3
Determine, stating reasons, the size of ∠P₁.
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Answer
Since ∠P₁ and ∠P₂ are on the same straight line, we have:
ext∠P1+ext∠P2=180°.
Substituting ∠P₂ = 82° into the equation gives:
ext∠P1+82°=180°ext∠P1=180°−82°=98°.
Therefore, ∠P₁ = 98°.
Step 4
Determine, stating reasons, the size of ∠L₁.
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Answer
Using the property of tangents to circles, we know that the angle between a tangent and a chord through the point of contact is equal to the angle in the alternate segment. Thus:
ext∠L1=∠N1=27°.
Therefore, ∠L₁ = 27°.
Step 5
Prove, stating reasons, that Δ KLP || Δ KNl.
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Answer
From the previous calculations, we established that ∠KLP = ∠KNI, as they are corresponding angles due to the transversal line LN.
Thus, by the Alternate Interior Angles Theorem, we conclude that Δ KLP || Δ KNl.
Step 6
Prove, stating reasons, that KL² = KN·KP.
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Answer
Using the property of segments in similar triangles derived from the previous proof of parallel lines: