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the diagram shows triangle ABD and triangle BCD ABC is a straight line BCD is a quadrilateral triangle angles DAB=25 degrees work out the size of the triangle marked x give a reason for ur answer

the diagram shows triangle ABD and triangle BCD ABC is a straight line BCD is a quadrilateral triangle angles DAB25 degrees work out the size of the triangle ma class=

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Answer:

25

Step-by-step explanation:

First step is to imagine a line that comes straight down from angle b.

This forms a 90 angle AND perfectly bisects angle b.

A triangle has 180 degrees and the angles we currently know are 25 and 90. add those two together and you get 115.

Subtract that from 180 and you get 65 for one part of angle b.

Since the line perfectly bisects angle b, the other side is also 65.

Now, we have the entire triangle DAB.

Angle B is 65x2=130

Angle A is 25

180 degrees in a triangle

130+25=155 degree that we know.

180-155=25 degrees

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