\fdO'^ - Old Forge Coal Mines

234 SURVEYING.
adjacent sides of the required rectangle. At B erect an
indefinite perpendicular B E to A B, and at D erect an in-
definite perpendicular DF to AD. These perpendiculars
will intersect at G^ and the
resulting figure A BCD will
be the required rectangle. Its
area is the product of the
length A D by the_width^ B.
TD" = BTf - ~AB\ 'BT>^ =
9 in. A B =2.25 in. ; ; hence,
'AD^ = 9 in. - 2.25 in. = 6.75
Fig. 56.
in. 4/6.75 = 2.598 in. = side
A D. 2.598 in. X 1.5 = 3.897 sq. in., the area of the required
rectangle.
(618) (See Fig. 57.) With
the two given points as cen-
ters, and a radius equal to
3.5'^ 2 = 1.75'= If', describe
short arcs intersecting each
other. With the same radius
and with the point of intersec-
tion as a center, describe a
circle; it will pass through
the two given points. Fig. 57
(619) A B \n Fig.
C
Fig. 68.
58
is the given line, A the given
point, A C and C B = A B.
The angles A, B, and C are
each equal to 60°. From B
and C as centers with equal
radii, describe arcs intersect-
at D. The line A D bi-
inga
sects the angle A ;
angle B A D = 30°.
hence,
(620) Let A B in Fig. 59 be one of the given lines,
whose length is 2 in., and let A C, the other line, meet A B
j^t A^ forming an angle of 30°. From A and B as centers,