CHAPTER 4
Circular Measure
13
MODE
2
1
2
6
0
SHIFT
a
b
/
c
X
2
X
1
1
2
2
x
2
SHIFT
a
b
/
c
X
0
sin
X
6
DGR
È
Ans
1
RCL
–
M+
=
=
=
MODE
M+
DGR
È
Ans
0
STO
RCL
M
M+
SHIFT
x
2
AOB is a sector of a circle with centre at O and radius 2cm. Find the area
of the shaded region.
OPERATION
1
. First enter
Rad
(radian) mode.
2
. Calculate the area of sector using the formula
θ
2
2
1
r
and store the calculated result.
3
. Now calculate the area of the triangle
AOB
using the formula
θ
sin
2
1
2
r
.
4
. The area of the shaded region is
Therefore, the area of shaded region is approximately 0.3623cm
2
, ignoring the negative
sign.
Show that the length of arc AB in the above example is approximately 2.0944cm.
Press
to clear the memory stored in M.
Example 1
R
0
1
ª
2X2
2
X sin 60
–
1.732050808
Ans-M
-0.362344294
A
O
60°
B
2cm
2cm
1
ª
2X 60
–
X2
2
2.094395102
