Question

using ruler and compass only construct a∆ABC in which ∆ A =120° and AB =AC=4 cm.​

Answer 1

Answer:

Steps:

1. First draw BC=5cm.

2. At B, draw an angle of 120

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. Along the direction, mark off BA=6.5cm using compasses.

3. Join AC. Thus △ABC is completed.

To sketch the circum-circle, we do the following:

1. Construct the perpendicular bisector of AB.

2. Construct the perpendicular bisector of BC.

3. Mark the point of intersection of both the perpendicular bisectors as O.

4. With O as center and OA as radius, draw a circle. This is the circum-circle of the △ABC.

Now, in order to find the point D which is equidistant from AB and BC, we construct the angle bisector of ∠ABC. Any point on it is equidistant from AB and BC. So, we find the point at which this angle bisector intersects the circum circle and name it D. Thus ABCD is the required cyclic quadrilateral.

Step-by-step explanation:

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