Lab Manual: Tangents drawn from an External Point | Lab Manuals for Class 10 PDF Download

Objective

Tangent
A line touchingthe circle at a point is called a tangent to the circle.

Prerequisite Knowledge

• Tangent to a circle.
• Length of a tangent.

Materials Required
Glazed papers, a white chart paper, sketch pens, a pair of scissors, geometry box, fevicol.

Procedure

• Cut a circle of any radius from a glazed paper and paste it on a white chart paper.
  
• Take any point P on the circle.

• From P, fold the paper in such a way that it just touches the circle at P. Press it and unfold to get a tangent PA.
  
• From A, fold the paper to get tangent AQ.
  
• Fold the circle along OA.
• Join OP, OA, OQ.
  

Observation
Students observe that point P coincide with Q
∴ AP = AQ

Result
Thus it is verified that lengths of tangents drawn from an external point to a circle are equal.

Learning Outcome
Students will learn how to measure tangents from an external point to a circle by using paper folding.

Activity Time

• Draw two tangents from a point P to a circle of radius 3 cm. If its distance from the centre is 10 cm, measure the lengths of the tangents. Are they equal ?
• In the adjoining figure, prove that AD+BC = AB+CD
  
• In the adjoining figure, find PQ and PR.