The Student Room Group

P2 maths-help pls!

1)prove that

tanx + cot x = 2cosec(2x)

2) a population of deer is introduced into a park. the population 'p' at time 't' years after the deer have been introduced is modelled by :

P = 2000a^t / 4 + a^t

'a' is a constant. given that there are 800 deer in the park after 6 years, and 'a' is 1.1776,

use the model to predict the number of years needed for the population of deer to increase from 800 to 1800.

Thanks
1) LHS = sinx/cosx + cosx/sinx
= (sin^2x + cos^2x)/sinxcosx
=2/sin2x
= RHS
Reply 2
2) This is pretty straight forward.....

1800 = 2000a^t / 4 + a^t
1800(4+a^t) = 2000a^t
7200 + 1800a^t = 2000a^t
7200 = 200a^t

36 = a^t

Now you need to take logs here to get t

ln 36 = ln a^t
ln 36 = t ln a (logs rule)

t = ln 36 / ln a

Insert the value of A to find T
t = 21.9 or 22 years

Your given that it took 6 years to get a population of 800
so the difference = 22 - 6

answer = 16 years
Reply 3
xskater
2) This is pretty straight forward.....

1800 = 2000a^t / 4 + a^t
1800(4+a^t) = 2000a^t
7200 + 1800a^t = 2000a^t
7200 = 200a^t

36 = a^t

Now you need to take logs here to get t

ln 36 = ln a^t
ln 36 = t ln a (logs rule)

t = ln 36 / ln a

Insert the value of A to find T
t = 21.9 or 22 years

Your given that it took 6 years to get a population of 800
so the difference = 22 - 6

answer = 16 years


ahhh. thank u

Latest