Show that =1 A trigonometric expression in a fractional form. The numerator is cos squared of (45 degrees plus theta) plus cos squared of (45 degrees minus theta). The denominator is tan of (60 degrees plus theta) multiplied by tan of (30 degrees minus theta).

L.H.S: = [∵ ]= [∵ ]= = [∵ cos2 θ + sin2 θ = 1]= [∵ ]= 1:R.H.S

Q13 of 120 Page 95

Show that =1

L.H.S:

= [∵ ]

= [∵ cos² θ + sin² θ = 1]

= [∵ ]

= 1

:R.H.S

If 2 sin² θ -cos² θ =2, then find the value of θ.

Show that =1

An observer 1.5 m tall is 20.5 m away from a tower 22 m high. Determine the angle of elevation of the top of the tower from the eye of the observer.

Questions · 120

8. Introduction to Trigonometry and Its Applications

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