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Mathematics 7 Online
OpenStudy (hyuna301):

inverse trigonometry question.....

OpenStudy (hyuna301):

OpenStudy (hyuna301):

question no. 21 and 22

OpenStudy (hyuna301):

@Sachintha

OpenStudy (welshfella):

the series in the parentheses are geometric so you can find their sum to infinity using the formula a1 / (1 - r). This will givw us an equation in x to solve.

OpenStudy (welshfella):

sin-1[ x / (x - x/2)] + cos-1 [x^2 / (1 - x^2/2)] = pi/2

OpenStudy (hyuna301):

but the series have alernate + and - sign... can we use sum of geometric series in such questions?????

OpenStudy (welshfella):

OH sorry - theres a mistake there the common ratio in the first one is -1/x not 1/x and also for second r = -1/X^2.

OpenStudy (welshfella):

so that should be sin-1[ x / (x + x/2)] + cos-1 [x^2 / (1 + x^2/2)] = pi/2

OpenStudy (hyuna301):

oh thanks a lot i know the next prosedure but was stuck in this step

OpenStudy (welshfella):

yw - its been a long time since i did these - I'm not sure about the next procedure - so can you tell me! lol!

OpenStudy (hyuna301):

it is one of the property, if, sin x + cos y = pi/2 then , x = y

OpenStudy (welshfella):

hmmm well i thought i understood tell me more

OpenStudy (hyuna301):

i think so , there is a correction in the sum of series in arc sin the sum should be , x/( 1+ x/2) am i correct ?

OpenStudy (welshfella):

oh yes that was a typo

OpenStudy (hyuna301):

next step .. x / (1 + x/2) = x^2 / ( 1+ X^2/2) x / ( 2 + x ) = ^2 / ( 2 + x^2 ) after evaluating i got , x = 1

OpenStudy (hyuna301):

can u pls help me in question no. 22

OpenStudy (welshfella):

sorry i have to go for 1/2 hour . If you haven't had help by then i will

OpenStudy (hyuna301):

ok

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