Page 11 - Trigonometry
P. 11
Example 3:
From the diagram on the left
derive an expression for the length
X.
Let the base side of the right angle
triangle be Y, then
tan( ) =
If the other angles in the isosceles
are Z, then
sin( ) sin( )
=
However + 2 = 180 ⇒ = 90 − ,
2
sin (90 − ) = sin(90) cos ( ) − cos(90) sin ( )
2 2 2
= cos ( )
2
Leaving,
sin( ) 1
= cos ( )
2
Inverting,
=
sin( )
cos ( )
2
7
