VERY EASY maths question!?

circumference = 2pi(r)
=2pi*21
=42pi
but we only need a quarter
=10.5pi
=32.99 (using pi = 3.142)
plus the two radius measurements
=32.99+42
=74.99

Let C = curved length
C = (1/4) (2 π r )
C = (1/4) (2 x 22/7 x 21)
C = (1/4) (132)
C = 33 cm

P = 21 + 21 + 33 cm
P = 75 cm

(21 x 2) x 22/7 x 1/4 + 21 x 2
= 42 x 22/28 + 42
= 3 x 22/2 + 42
= 3 x 11 + 42
= 33 + 42
= 75

radius=21cm

thus length of arc+2x radius=(2 x pi x r/4)+42
roughly=32.99+42
roughly= 74.99cm

:-) ;)

You could also use the arc length equation

Which is s = rθ

s being the arc length, length you want, r the radius, and θ the angle (in radians).

90 degrees = π/2 radians
so s = 21 * (π/2)

s = 32.986

so 32.986 + 21 + 21 = 74.99

21cm + 21cm + (2*pi*(21cm/4))
42cm + 32.9cm
74.9cm

There are two even sides - each is 21 cm. That makes 42 cm so far. The other side (curved) is 1/4 of a circle. The radius of that circle is 21 cm which makes the diameter 42 cm.. 42 X 3.14 = 131.88. 131.88 divided by 4 = 32.97. 32.97 + 42 = 74.97

The region is bounded by two radii of length 21 cm and a circular arc of length 2*Pi*21/4=0.5*Pi*21=0.5*3.14*21=32.97 approximately => the perimeter is 2*21+32.97=42+32.97=74.97. Should you take more digits for Pi, you'll get a more precise answer

the pic shows a sector wth radius = 21 cm

so perimetre = ( 2r) + (2*pi*r/4)

= (2*21 ) + ( 2* 22/7 * 21 /4)

= 42 + (2*22 * 3/4)

= 42 + (11*3 )

= 42 +33


=75 cm

Hehehe. The two straight sides add up to 42 cm and the 'quarter' circle has a -total- circumference of 2*21*pi cm, so 1/4 of it is 21*pi/2. You take it from there <g>

HTH,
Doug