The simplified value of $(sec x sec y + tan x tan y)^{2} - (sec x tan y + tan x sec y)^{2}$ is :
1). -1
2). 0
3). $sec^{2}x$
4). 1
(secx . secy + tanx . tany)2 –(sec x . tan y + tan x . sec y)2
= sec2 x . sec2 y + tan2 x . tan2y +2 sec x . sec y . tan x . tan y –sec2 x . tan2 y – tan2 x . sec2y – 2sec x . sec y . tan x . tan y
= sec2 x . sec2y + tan2x . tan2 y –sec2 x . tan2y – tan2 x . sec2y
= sec2x . sec2y – sec2x . tan2y –tan2x . sec2y + tan2 x . tan2y
= sec2x (sec2y – tan2y) – tan2x(sec2y – tan2y)
= sec2x – tan2x = 1.
4. Simplify the following: [(cos A + cos B)/(sin A – sin B)] + [(sin A + sin B)/(cos A – cos B)]
5. If sin P + cosec P = 2, then the value of sin7P + cosec7P is
6. If 5(sin A cos3 A + sin3 A cos A)3 – 2 sin3 A cos3 A = x sin3 2A, find the value of x.
7. If \(0 \le \theta \le \frac{\pi }{2}\) and √3 cos θ + sin θ = 2, then what is the value of θ?
8. What is the simplified value of $\sqrt{\frac{cosecA-1}{cosecA+1}}$
9. The time taken by a train 160 m long, running at 72 km/hr, in crossing an electric pole is