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Yeah it's just one of those things you need to know, apparently.

I have no idea how I'm going to remember the different values for sin cos and tan of 30, 45 and 60, I'm doomed I tell ya.

[EDIT] In visesh's diagram remember sohcahtoa. Sin = Opp / Hyp. As for where the diagram itself comes from, it's just one of two triangles you need to have burned into the back of you brain. I'm sure if visesh is kind enough, he'll post the other one for us.

I have no idea how I'm going to remember the different values for sin cos and tan of 30, 45 and 60, I'm doomed I tell ya.

[EDIT] In visesh's diagram remember sohcahtoa. Sin = Opp / Hyp. As for where the diagram itself comes from, it's just one of two triangles you need to have burned into the back of you brain. I'm sure if visesh is kind enough, he'll post the other one for us.

sin (A+B)=sin A cos B + cos A sin B

sin 60°= sin (30°+30°)

= sin 30° cos 30° + cos 30° sin 30°

= 2 sin 30° cos 30°

= 2 (1/2) ((√3)/2)

= (√3)/2

sin 60°= sin (30°+30°)

= sin 30° cos 30° + cos 30° sin 30°

= 2 sin 30° cos 30°

= 2 (1/2) ((√3)/2)

= (√3)/2

AC = √ 3 because it is a non-hypotenuse side of a triangle with sides 1 and hypotenuse 2, and √ (2²-1²) = √3 by pythagoras.

BC = 1 because AB = 2 and the white + red triangles together make an equilateral triangle.

angle BAC = 30 degrees for the same reason.

In order to work out sin 60, use AC as the hypotenuse and AB as the opposite side.

BC = 1 because AB = 2 and the white + red triangles together make an equilateral triangle.

angle BAC = 30 degrees for the same reason.

In order to work out sin 60, use AC as the hypotenuse and AB as the opposite side.

I think that you might want to upgrade your calculator. Casio now offer "Natural Display" calculators (allowed in exams) that will show root(3)/2 (but it shows it how you would write it) when you key in sin60, and all of the other ones listed above.

See the product page on the casio website.

http://www.casio.co.uk/prod/product.asp?ID=1749

I bought mine for about £5 at WHSmith.

See the product page on the casio website.

http://www.casio.co.uk/prod/product.asp?ID=1749

I bought mine for about £5 at WHSmith.

Joe_87

I have no idea how I'm going to remember the different values for sin cos and tan of 30, 45 and 60, I'm doomed I tell ya.

You could get away with just learning sin, the cos values are just sin values backwards, and tan is just sin/cos, or just remember:

Angle------0°----------30°-------45°----------60°--------90°

Sin--------0-----------1/2------1/(√2)-------(√3)/2--------1

Cos--------1---------(√3)/2-----1/(√2)--------1/2---------0

Tan--------0---------1/(√3)-------1-----------√3----------∞

samd

I think that you might want to upgrade your calculator. Casio now offer "Natural Display" calculators (allowed in exams) that will show root(3)/2 (but it shows it how you would write it) when you key in sin60, and all of the other ones listed above.

See the product page on the casio website.

http://www.casio.co.uk/prod/product.asp?ID=1749

I bought mine for about £5 at WHSmith.

See the product page on the casio website.

http://www.casio.co.uk/prod/product.asp?ID=1749

I bought mine for about £5 at WHSmith.

This is for C1 (non calc)

wacabac

You could get away with just learning sin, the cos values are just sin values backwards, and tan is just sin/cos, or just remember:

0° 30° 45° 60° 90°

Sin 0 1/2 1/(√2) (√3)/2 1

Cos 1 (√3)/2 1/(√2) 1/2 0

Tan 0 1/(√3) 1 √3 ∞

0° 30° 45° 60° 90°

Sin 0 1/2 1/(√2) (√3)/2 1

Cos 1 (√3)/2 1/(√2) 1/2 0

Tan 0 1/(√3) 1 √3 ∞

simple.

sin²x+cos²x=1

divide through by cos²x

sin²x+cos²x=1

divide through by cos²x

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can someone please explain what principle domain is and why the answer is a not c?Maths

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