Thursday 24 April 2014

TRIGONOMETRY D1



If Sin15x = 0.5 and 00 x 3600, solve for x.

Solution

Sin15x = 0.5 ………….. (i)
Sin300= 0.5………….. (ii)

equating (i) and (ii),

15x = 300
15x = 300
15      15

x = 20
From the given question we see that sine is positive.

From the range of 00 up to 3600 sine is positive in the 1st and 2nd quadrants.
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

In the 1st quadrant,

x= 100


In the 2nd quadrant,

SinӨ= Sin(1800 – Ө)

Sin300= Sin(1800 – 300) = Sin1500
Then,
Sin15x = 0.5 ………….. (i)
Sin1500= 0.5………….. (iii)

Equating (i) and (iii),

15x = 1500
15x = 1500
15       15

x = 100

Hence x = 20 or x = 100 answer

TRY THIS…………

If Sin(2x-10) = 0.8 and 00 x 3600, solve for x.

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