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As level Pure mathematics Question

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nid404:

--- Quote from: spiderman on September 03, 2009, 11:53:05 am ---sin(2@+60)=0.3584
find the least 2 +ve values of @...



Pls someone help me.......in solving d sum

--- End quote ---

this one's a litlle tricky but you can't be fooled by these cie crappy ppl

here u go
sin(2 theta + 60)=0.3584
so
2 theta+60=sin-10.3584
2 theta+60=21.0019...
now comes the part....u know ull get  negative answer if u use this value of the inverse
so u take 180-21.0019 and theta + 360 cuz these also have value of inverse is 0.3584 (translation and periodic property)
i hope u got this part
so then,
2 theta+60=158.998...
2 theta= 158.998...-60
theta=49.5
and then
2 theta+60=381.001967...
2 theta= 381.001967-60
theta= 160.5

astarmathsandphysics:

--- Quote from: xxemoxx on August 28, 2009, 07:54:36 pm ---thankyou! I slved that Q sometime back
can u help me with this one..
A(7,2) C(1,4) are two vertices of a square ABCD
(a)find the equation of the diagonol BD
(b) Find the coordinates of B and of D

--- End quote ---
gradient of AC=(4-2)/(1-7)=-1/3
so gradient of perpendicular line=-1/(-1/3)=3
Also the mid point of AC is a point on BD. Mid point of AC=((7+1)/2,(2+4)/2)=(4,3)
Equation of BD is y=3x+c sub (4,3) in to find c
3=3*4+c so c=-9 and y=3x-9 is equation of BD.

the vector from A to C=(-6,2) so the vector from the midpoint is (-3,1) hence since BD is perpendicular the vector from the centre to eith B or D is (1,3) hence the coordinates are (4,3)+(1,3)=(5,6) or (4,3)-(1,3)=(3,0)

Ghost Of Highbury:

--- Quote from: astarmathsandphysics on September 27, 2009, 08:35:57 pm ---gradient of AC=(4-2)/(1-7)=-1/3
so gradient of perpendicular line=-1/(-1/3)=3
Also the mid point of AC is a point on BD. Mid point of AC=((7+1)/2,(2+4)/2)=(4,3)
Equation of BD is y=3x+c sub (4,3) in to find c
3=3*4+c so c=-9 and y=3x-9 is equation of BD.

the vector from A to C=(-6,2) so the vector from the midpoint is (-3,1) hence since BD is perpendicular the vector from the centre to eith B or D is (1,3) hence the coordinates are (4,3)+(1,3)=(5,6) or (4,3)-(1,3)=(3,0)


--- End quote ---

sir, wat is this concept named as? i mean, wat is the rule u applied in ur last sentence called?

astarmathsandphysics:
Can you quote the part you arequerying

Ghost Of Highbury:
the vector from A to C=(-6,2) so the vector from the midpoint is (-3,1) hence since BD is perpendicular the vector from the centre to eith B or D is (1,3) hence the coordinates are (4,3)+(1,3)=(5,6) or (4,3)-(1,3)=(3,0)


the above, wat is the concept called? the concept which states abt the sign switching and vectors..just wanted to know so i can look it up and learn it.! plz help

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