Students can go through AP 7th Class Maths Notes Chapter 9 Perimeter and Area to understand and remember the concepts easily.
Class 7 Maths Chapter 9 Notes Perimeter and Area
→ Perimeter is the distance around the outside of a shape.
→ Area measures the space inside a shape.
→ Perimeter of triangle ABC is AB + BC + AC.
→ Perimeter of square ABCD is 4 × AB.
→ Perimeter of rectangle ABCD is 2(AB + CD).
→ 
→ 
→ Perimeter (do) circumference of semicircle :
P = \(\frac{2 \pi r}{2}\) + 2r
P = πr + 2r
P= r(π + 2)
P = r(\(\frac{22}{7}\) + 2)
P = r(\(\frac{22 + 14}{7}\))
P = \(\frac{36 \mathrm{r}}{7}\)
→ Circumference of circle = 2πr
= π . 2r = πd
→ Diameter of a circle is 2 times its radius. The diagonal of a parallelogram divides it into two congruent triangles of equal area.
Solution:
Suppose ABCD is a parallelogram of area 40 sq.cm.
AC is the diagonal, then
ar ΔABC = ar ΔACD = \(\frac{40}{2}\) = 20 cm2
→ All the congruent triangles are equal in area but the triangles equal in area need not be congruent.
→ The distance around a circular region is known as it circumference.
→ π = \(\frac{22}{7}\) = 3.14.