# Maths formulas for class 10 chapter- Constructions Formula

Jul 08, 2022, 16:45 IST

For drawing geometrical figures such as a triangle, a circle, a quadrilateral, a polygon, etc. with given measurements some basic geometrical instruments are needed

• A pair of set-squares, with angles 90°, 60° and 30° and other with angles 90°, 45° and 45°
• A divider
• A compass with provision of fitting a pencil at one end.
• A protractor

But a geometrical construction is the process of drawing a geometrical figure using only two instruments- an un graduated ruler and a compass. In construction where measurements are also required, one may use a graduated scale and protractor also.

## Basic Constructions

• To construct the bisector of a given angle.
• To construct the perpendicular bisector of a given line segment. 3 To construct and angle of 30°, 45°, 60°, 90°, 120° at the initial point of a given ray.

### Construction of a Tangent to a Circle

• To draw the tangent to a circle at a point on it without using the center of the circle.
• To draw a tangent to a circle from a point outside the circle using its center.
• To draw tangents to a circle from a point outside the circle without using its center.
• To construct an incircle of the triangle whose sides are given to be a, b, and c.
• To construct the circumcircle of the triangle with sides a, b and c.

### Construction of Triangles

• To construct a triangle with a given base, vertical angle, and altitude through the vertex.
• To construct a triangle with a given base, given vertical angle, and the median through the vertex.
• To construct a triangle similar to a given triangle as per the given scale factor.