Class 8 Maths - BIHAR
Quadrilaterals
In this chapter, Class 8 Bihar Board students will explore quadrilaterals, which are four-sided closed polygons. You will learn about the angle sum property of quadrilaterals, stating that the sum of all four interior angles is always 360 degrees. The chapter covers different types of quadrilaterals including parallelograms, rectangles, squares, rhombuses, trapeziums, and kites, along with their unique properties regarding sides, diagonals, and angles. Mastering this chapter is crucial for your board exams as it forms the geometric foundation for advanced proofs and constructions in higher classes, frequently appearing in both short and long answer sections.
Start Learning FreeKey Concepts
Polygon and Quadrilateral
A polygon is a closed figure made of three or more line segments, and a quadrilateral is a specific polygon with exactly four sides, four vertices, and four angles.
Angle Sum Property
The sum of the four interior angles of any quadrilateral is always equal to 360 degrees.
Parallelogram
A quadrilateral in which both pairs of opposite sides are parallel and equal, and opposite angles are also equal.
Special Parallelograms
A rhombus has all four sides equal with diagonals intersecting at 90 degrees, a rectangle has all 90-degree angles with equal diagonals, and a square has both properties combined.
Trapezium and Kite
A trapezium is a quadrilateral with at least one pair of parallel sides, while a kite has two pairs of adjacent sides that are equal in length.
Important Formulas
Board Exam Info
In the Bihar Board Class 8 Mathematics examination, the chapter on Quadrilaterals typically carries around 6 to 10 marks. Common question types include finding an unknown angle using the angle sum property, identifying special types of quadrilaterals based on given properties, and simple word problems based on the properties of parallelograms and rhombuses.
Frequently Asked Questions
What is the difference between a parallelogram and a trapezium?
A parallelogram has both pairs of opposite sides parallel and equal, whereas a trapezium only needs to have one pair of parallel sides.
Are all squares rectangles?
Yes, all squares are rectangles because they have all the properties of a rectangle, such as four 90-degree angles and opposite sides being parallel and equal.
Why is the sum of angles in a quadrilateral always 360 degrees?
A quadrilateral can be divided into two triangles by drawing a diagonal. Since the angle sum of one triangle is 180 degrees, two triangles make 180 * 2 = 360 degrees.
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