Page 169 - Mathematics_Form_Two

Trigonometry

Example 8�1 tan A = BC

Study the following triangle and answer AB
the questions that follow. AB BC
sin C = , cos C = , and
AC AC
AB
FOR ONLINE READING ONLY
tan C = .
BC

Example 8�2

YZ Mathematics for Secondary Schools
Given that sin X = , draw a
XZ

(a) Use angle C from ∆ABC to label right-angled triangle that represents this
the hypotenuse, opposite, and information and determine each of the
adjacent sides. following ratios:

(a) sin Z
(b) Use the triangle to write the
trigonometric ratios for angles A (b) cos Z
and C. (c) tan Z

(d) cos X
Solution
(a) With reference to angle C, the (e) tan X
triangle ABC is labelled as Solution
shown in the following figure. The respective triangle is shown in the
following figure.

(a) sin Z= XY (d) cos X= XY

From the figure, AB is the opposite XZ XZ
side, BC is the adjacent, and AC is (b) cos Z= YZ (e) tan X= YZ
the hypotenuse. XZ XY

BC AB AB XY
(b) sin A = , cos A = , tan A = (c) tan Z=
AC AC BC YZ

163
Student's Book Form Two

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