Points B, D, E and F lie on a circle - Edexcel - GCSE Maths - Question 16 - 2020 - Paper 3
Question 16
Points B, D, E and F lie on a circle.
ABC is the tangent to the circle at B.
Find the size of angle ABD.
You must give a reason for each stage of your working.
Worked Solution & Example Answer:Points B, D, E and F lie on a circle - Edexcel - GCSE Maths - Question 16 - 2020 - Paper 3
Step 1
Find angle DFE
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Answer
Since angle DFE is an angle in a cyclic quadrilateral (BDFE), we can use the property that opposite angles in cyclic quadrilaterals add up to 180 degrees. Therefore, we have:
extangleDFE=180−100=80
Step 2
Find angle EBF
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Answer
Next, we know that angle EBF, being an angle subtended by arc EF at point B, is equal to angle DFE. Thus, we can write:
extangleEBF=80
Step 3
Find angle ABD
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Answer
Finally, angle ABD is the exterior angle at point B, formed by line AB and the chord EF. Exterior angles are equal to the sum of the opposite interior angles. Therefore, we have: