Basic Engineering Mathematics, Fifth Edition

222 Basic Engineering Mathematics

Table 25.1Formulae for the areas of common shapes

Area of plane figures

Square x

x

Area=x^2

Rectangle

I

b

Area=l×b

Parallelogram

h

b

Area=b×h

Triangle

h

b

Area=

1

2

×b×h

Trapezium

h

b

a

Area=

1

2

(a+b)h

Circle

r

Area=πr^2 or

πd^2

4

Circumference= 2 πr

Radian measure: 2πradians=360 degrees

Sector of circle

s

r



Area=

θ◦

360

(πr^2 )