SmarterEd

Aussie Maths & Science Teachers: Save your time with SmarterEd

  • Login
  • Get Help
  • About

Trigonometry, SPEC2 2020 VCAA 4 MC

Let  `f(x) = sqrt(x - 1)/x`  over its implied domain and  `g(x) = text(cosec)^2 x`  for  `0 < x < pi/2`.

The rule for  `f(g(x))`  and the range, respectively, are given by

  1. `f(g(x)) = text(cosec)^2(sqrt(x - 1)/x), [1, ∞)`
  2. `f(g(x)) = text(cosec)^2(sqrt(x - 1)/x), [2, ∞)`
  3. `f(g(x)) = sin(x)cos(x), [−0.5, 0.5]\\ {0}`
  4. `f(g(x)) = sin(x)cos(x), (0, 1/2)`
  5. `f(g(x)) = 1/2 sin(2x), (0, 1/2]`
Show Answers Only

`E`

Show Worked Solution

♦♦♦ Mean mark 28%.
`f(g(x))` `= sqrt(text(cosec)^2(x) – 1)/(text(cosec)^2(x))`
  `= sqrt(cot^2(x))/(text(cosec)^2(x))`
  `= (cos(x))/(sin(x)) · sin^2(x)`
  `= cos(x)sin(x)`
  `= 1/2 sin(2x)`

 
`text(Given)\ \ 0 < x < pi/2`,

`text(Range)\ \ f(g(x)) :\ \ (0, 1/2]`

`=>E`

Filed Under: Trigonometry (SM) Tagged With: Band 6, smc-1150-30-Composite

Trigonometry, SPEC2 2016 VCAA 1 MC

The cartesian equation of the relation given by  `x = 3 text(cosec)^2 (t)`  and  `y = 4 cot (t) - 1`  is

A.  `(y + 1)^2/16 - x^2/9 = 1`

B.  `(y + 1)^2 = (16 (x + 3))/3`

C.  `x^2/9 + (y + 1)^2/16 = 1`

D.  `4x - 3y = 15`

E.  `(y + 1)^2 = (16 (x - 3))/3` 

Show Answers Only

`E`

Show Worked Solution
`x/3` `= text(cosec)^2(t)`  
`(y+1)/4` `=cot (t)`  

 

`sin^2(t) + cos^2(t)` `= 1`
`1 + cot^2(t)` `= text(cosec)^2(t)`
`text(cosec)^2(t) – cot^2(t)` `= 1`
   
`(x/3) – ((y + 1)/4)^2` `= 1`
`(y + 1)^2/16` `= x/3 – 1`
`(y + 1)^2` `= (16 (x – 3))/3`

 
`=>  E`

Filed Under: Trigonometry (SM) Tagged With: Band 4, smc-1150-30-Composite

Algebra, SPEC2-NHT 2018 VCAA 2 MC

Let  `f(x) = (sqrt(x + 1))/x`  and  `g(x) = tan^2 (x)`, where  `0 < x < pi/2`.

`f(g(x))` is equal to

  1. `sin (x) sec^2 (x)`
  2. `sec (x) tan^2 (x)`
  3. `cos (x) cot^2 (x)`
  4. `cos (x) text(cosec)^2 (x)`
  5. `text(cosec) (x) cos^2 (x)`
Show Answers Only

`D`

Show Worked Solution
`f(tan^2 (x))` `= (sqrt (tan^2(x) + 1))/(tan^2(x))`
  `= (sqrt(sec^2 (x)))/(tan^2(x))`

 
`0 < x < pi/2 => sqrt (sec^2(x)) = sec(x)`

`f(g(x))` `= (sec (x))/(tan^2(x))`
  `= (cos^2(x))/(sin^2(x) cos(x))`
  `= (cos(x))/(sin^2(x))`
  `= cos(x) text(cosec)^2 (x)`

 
`=>   D`

Filed Under: Trigonometry (SM) Tagged With: Band 4, smc-1150-30-Composite

Copyright © 2014–2025 SmarterEd.com.au · Log in