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Higher Maths Homework Help?
Solve:
3cosx + 2 = 4
2sin^2x = 1
3tan2x + 4 = 1
I know that these are trig equations and that I have to use the CAST diagram but I do not know how to actually do the question. Can someone help talk me through how I would do these questions?
2 Answers
- 9 years agoFavorite Answer
with each case, rearrange to get the trig function on its own
cosx = 2/3
sinx= (1/2)^0.5
tan2x= -1
trig identities state in the formula booklets that tan2x=(2tanx)/1-tan^2x
2tanx= -1 + tan^2 x
tan^2x -2tanx-1 =0
hidden quadratic will provide solutions for tan x
from this point you have to use a cast diagram, do inverse trig function to find the principle value of x
draw this angle on your cast diagram in the A quarter (top right)
for cos, draw same angle in bottom right quarter
sin-top left
tan-bottom left
trace the diagram from 0 anticlockwise, this will tell you the angles that satisfy the equation
Source(s): a level student - Anonymous9 years ago
That guys lying, x=7, 32 and infinity for each question respectively. The way i got the answers has looking deep into my soul and finding the answers of the heart and dividing by the planetary alignment.