In the diagram AB is parallel to DC.
Angle ABC = 70°
Angle ACD = 55°
Not drawn accurately
Show that triangle ABC is isosceles.
You must give reasons in your working.

Since m<BCA=m<CAB=55°, it follows that |AB|=|AC|, this means triangle ABC is isosceles.

Step-by-step explanation:

In the diagram AB is parallel to DC.

This means that, by the alternate interior angles theorem?

Also the sum of angles in a triangle should be 180° .

Since m<BCA=m<CAB=55°, it follows that |AB|=|AC|

Hence triangle ABC is isosceles.

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find the upper bound of the range.

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step-by-step explanation:

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