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Area Theorems — Flashcards

ICSE · Class 9 · Mathematics

25 flashcards for Area Theorems (ICSE Class 9 Mathematics) to test yourself on key terms and facts. Sample: "Why do two parallelograms on the same base"

35 questions25 flashcards3 formulas & key relations5 concepts

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An infographic showing the basic area formulas for a triangle, rectangle, and parallelogram, as a refresher before introducing area theorems.
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25 Flashcards·
Theorem 19Theorem 19 applicationArea formulaTheorem 20Theorem 20 applicationTheorem 20 conceptTheorem 21
Card 1Theorem 19

Why do two parallelograms on the same base and between the same parallels have equal area?

Answer

Step 1: Parallelograms on the same base have the same base length. Step 2: Between the same parallels means they have the same height. Step 3: Area of a parallelogram = base × height. Step 4: Since bo…

Card 2Theorem 19 application

Solve: The area of parallelogram AFEC is 140 cm². Find the area of parallelogram BFED if both are on the same base and between the same parallels.

Answer

Step 1: Parallelograms BFED and AFEC are on the same base and between the same parallels. Step 2: Parallelograms on the same base and between the same parallels are equal in area. Step 3: Area of BFED…

Card 3Area formula

Formula for the area of a parallelogram.

Answer

Formula: area of a parallelogram = base × height Here, base = length of the chosen side and height = perpendicular distance between that side and its opposite parallel side. Quick example: If base = 1…

Card 4Theorem 20

When do you use the rule 'the area of a triangle is half that of a parallelogram on the same base and between the same parallels'?

Answer

Use this rule when a triangle and a parallelogram share the same base and lie between the same parallels. Worked example: If a parallelogram has area 96 cm², then the triangle on the same base and bet…

Card 5Theorem 20 application

Solve: Triangle ABC and parallelogram ABDE are on the same base AB and between the same parallels AB and ED. If area of ABDE = 84 cm², find area of triangle ABC.

Answer

Step 1: Triangle ABC is on the same base and between the same parallels as parallelogram ABDE. Step 2: Area of a triangle = 1/2 × area of the parallelogram on the same base and between the same parall…

Card 6Theorem 20 concept

Why does a triangle have half the area of a parallelogram on the same base and between the same parallels?

Answer

Step 1: A parallelogram can be split by a diagonal into two equal triangles. Step 2: Each triangle has the same base and height as half of the parallelogram. Step 3: So each triangle has half the area…

Card 7Area formula

Formula for the area of a triangle.

Answer

Formula: area of a triangle = 1/2 base × height Here, base = base length and height = perpendicular altitude. Quick example: If base = 10 cm and height = 6 cm, area = 1/2 × 10 × 6 = 30 cm².

Card 8Theorem 21

Solve: Two triangles are on the same base and between the same parallels. Triangle 1 has area 18 cm². What is the area of Triangle 2?

Answer

Step 1: Triangles on the same base and between the same parallels are equal in area. Step 2: Therefore, Triangle 2 has the same area as Triangle 1. Step 3: Area of Triangle 2 = 18 cm². Answer: 18 cm²…

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Frequently Asked Questions

What are the important topics in Area Theorems for ICSE Class 9 Mathematics?
Key topics in Area Theorems include Basic ideas and figures between the same parallels, Theorem 19 and its corollary, Theorem 20: area of a triangle and a parallelogram, Theorem 21 and corollaries. Study these first, then practise questions on each for Class 9 exams.
How many flashcards are available for Area Theorems?
There are 25 flashcards for Area Theorems covering key definitions, facts and ideas. A few sample cards are shown on this page.
How should I revise Area Theorems for Class 9 exams?
Learn the core ideas first, then work through the 35 practice questions on Area Theorems. Revise definitions regularly and use flashcards for quick recall before the exam.

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