Cobby's Spesh Questions

[cobby]

Hey =]



Firstly, is there a general step by step process that i can adopt and apply to all questions in this form?
Secondly, how do i answer this? lul

Thanks =]

[Flaming_Arrow]

hint: sin is negative and tan is positive in that period

[cobby]

hint: sin is negative and tan is positive in that period

LEGEND!

[kurrymuncher]

OK,

cos x= -0.70

square both sides-    cosx^2= 0.49

cosx^2= 1-sinx^2

1-sinx^2=0.49

sinx^2=0.51

sin x= sqr root(0.51)

because sin is negative in the third quadrant, sin x = - sqr root(0.51)

For Tan x, tanx= sin/cos

so it is just (-sqr root(0.51))/ (-0.7)

sorry,i couldnt be bothered using latex

[Flaming_Arrow]

[cobby]

i got the cos x bit right(flaming arrows answer), but my calc keeps giving me a ridiculous answer for tan x.. i keep getting -.012 when the book says...sqr rt(51)/7...? :S :S :S

[kurrymuncher]

You must be stuffing up the brackets on the calc

[Flaming_Arrow]

=

[cobby]

=

oh kk, yeh i had them the other way around..woops..thanks flaming arrow

[Flaming_Arrow]

no worries.

[dekoyl]

This is from chapter 1 of the Essentials book right? (Q6)?
There's a way I was taught by using triangles.

[cobby]

This is from chapter 1 of the Essentials book right?
There's an easier way using triangles.

yeh chapter 1, is the easier way found later on in the chapter?
or another book?

[dekoyl]

This is from chapter 1 of the Essentials book right?
There's an easier way using triangles.

yeh chapter 1, is the easier way found later on in the chapter?
or another book?

Just the way I was taught. The didn't even cross my mind. I'm not sure if it's future proof but for this question (and the others in this chapter), draw a right angled triangle.
The length is -7. Height is and hypotenuse is 10.

[Damo17]

Example 4 on page 6 shows exactly how to work out this question.

[cobby]

This is from chapter 1 of the Essentials book right?
There's an easier way using triangles.

yeh chapter 1, is the easier way found later on in the chapter?
or another book?

Just the way I was taught. The didn't even cross my mind. I'm not sure if it's future proof but for this question (and the others in this chapter), draw a right angled triangle.
The length is -7. Height is and hypotenuse is 10.

ahh yes i understand that way..thanks dekoyl