Given that : AC = 6 ft. BD = 1 ft.
and cos C = 0.9
Now cos C^{2} = 1  sin^{2}C
or sin^{2}C =
1  cos^{2}C

Find q in fig. without
using trigonometric table or a calculator to find the value
of t functions.
Solution

A ladder leans against the side of a building
with its foot 12 ft from the building. How far from the ground
is the top of the ladder and how long is the ladder if it makes
an angle of 70^{0} with the ground ?
Solution
From fig., tan A = CB / AC \ CB =
AC tan A
\ CB = 12 tan 70 ^{0} = 12 (2.7)
= 32.4
The top of the ladder is 32.4 ft. above the ground. sec A = AB /
AC ; then AB = AC sec A = 12 (2.9) = 34.8 \
The ladder is 34.8 ft. long.
Angles In Standard Positions

With respect to a coordinate system, an angle
is said to be in "standard position" when its vertex
is at the origin of this rectangular coordinate system and its
initial side coincides with the positive of xaxis.

When the terminal side of an angle in standard
position falls in any quadrant, then the angle is said to be
"angle of that quadrant."

Index
2.1 Trigonometric Ratio of Acute Angles
2.2 Fundamental Relation between the trigonometric Ratios of an angle
2.3 Functions of General Angles or t Ratio
2.4 Tables of Trigonometric Function
Supplementary Problems
Chapter 3
