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Ab and c lie on a straight line BD=CD BCD=15 BAD=5 Work out x

1 Answer

3 votes

Answer:


x = 10

Explanation:

The attachment completes the question;

From the question, we have the following given parameters


BD = CD


\angle BCD = 15\deg


\angle BAD = 5\deg

Required

Solve for x

Since
BD = CD then


\angle CBD = \angle BCD --- Property: Base angle of an isosceles triangle


\angle CBD = \angle BCD = 15

Also, ABC is a straight line;

So:


\angle CBD + \angle DBA = 180 --- angle on a straight line

Substitute 15 for
\angle CBD


15 + \angle DBA = 180

Make
\angle DBA the subject


\angle DBA = 180 - 15


\angle DBA = 165

Considering triangle DBA


\angle DBA + \angle BAD + x = 180 ---- angles in a triangle

Substitute 165 for
\angle DBA and 5 for
\angle BAD


165 + 5 + x = 180

Make x the subject


x = 180 - 165 -5


x = 10

Ab and c lie on a straight line BD=CD BCD=15 BAD=5 Work out x-example-1
User Dharmik Patel
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