Question #89a8f

1 Answer
Apr 5, 2017

#78^@69; 258^@69#

Explanation:

Use 4 trig identities:
#sin t - cos t = sqrt2sin (t - pi/4)#
#sin t + cos t = sqrt2sin (t + pi/4)#
sin (a - b) = sin a.cos b - sin b.cos a
sin (a + b) = sin a.cos b + sin b.cos a
In this case:
#3sqrt2sin (t - pi/4) = 2sqrt2sin (t + pi/4)#
#3sin (t - pi/4) = 2sin (t + pi/4)#
#3((sqrt2sin t)/2 - (sqrt2cos t)/2) = 2((sqrt2sin t)/2 + (sqrt2cos t)/2)#
#(sqrt2/2)sin t - (5sqrt2)/2cos t = 0#

sin t - 5cos t = 0
Call #tan x = sin x/(cos x) = 5# --> #x = 78^@69#
sin t cos x - sin x cos t = 0
sin (t - x) = sin (t - 78.69) = 0

Unit circle gives 2 solutions
#t - 78.69 = 0# --> #t = 78^@69#
#t - 78.69 = 180# --> #t = 258^@69#