AP EAMCET2006MathematicsTrigonometric Ratios & Identities
If x= 15^ , y= cosec 75^ and z=4 18^ , then :
Options
- Ax < y < z
- By < z < x
- Cz < x < y
- Dx < z < y
Correct answer
A. x < y < z
Step-by-step solution
x= 15^ = (45^ -30^ )= 45^ - 30^ 1+ 45^ 30^ = 1- 1 3 1+ 1 3 = 3 -1 3 +1 = ( 3 -1)^2 3-1 = 3+1-2 3 2 =2- 3 and y= cosec 75^ = 1 (45^ +30^ ) = 1 45^ 30^ + 45^ 30^ = 1 3 2 2 + 1 2 2 = 2 2 3 +1 3 -1 3 -1 = 2 2 ( 3 -1) 3-1 = 6 - 2 and z=4 18^ =4 ( 5 -1 4 )= 5 -1 It is clear from above that (2- 3 ) < ( 6 - 2 ) < ( 5 -1) x < y < z