348 NICHOLLS'3 SEAMANSHIP AND NAUTICAL KNOWLEDGE

Rectangle,—

Area—length X breadth=Z X b

Triangle.—

(i) Area=half baseXheight=J axh
(ii) area= y5(5_a) (s—b) (s—c)

where s=-| (a+6+c)
(iu) area=-| a b sin C=^ a c sin B

Circle.—

Circumference=2:rr

22

71=3*14:16, or -r approximately

r is the radius of the circle

Ring.-

Area=7T jK2—7rr2=7c (R2— r*)
=* (JS+r) (fi-r)

Arc of Circumference = 5»oo
Area of Sector =1^0
Area of Segment =J r2 (6—Sin 8°)
6°
where 6 = g«^«
Box-shaped body.—
The surface area is the sum of the areas of
its six sides.
Area=top+bottom+2 sides+2 ends
Yolume=length Xbreadth xdepth=Jx&X<t