Yr 11 maths (1 Viewer)

[Gator]

anyone doing 3 unit yr 11 maths


if so do u know how to find cos sin tan without calculator?

 

[Trev]

To an extent.
What do you mean specifically?
There are the 30deg, 60deg, 90deg triangle (sides 1, sqrt3, 2) and the 45deg, 45deg, 90deg triangle (sides 1,1,sqrt2). Using this you can find out the exact values of those angles, and using the exact values of those angles (and the formulae of sin(a+b) for example, I forget what they are called) you can find out exact values of angles such as 15deg.........

 

[JamiL]

or u can put 4 eg tanx (where x is a remarkable angle) in2 the calculator.. if u get an answer which is not a rational number square it... n u will get 4 eg 3/4...
therefore tan x=(root3)/2... i dont remember em, why that is not maths.
yes n if they ask u like sin 15, that is sin(45-30)=sin45cos30-sin30cos45 (which dont ask me wot that is ill have 2 think)

 

[Trev]

yes n if they ask u like sin 15, that is sin(45-30)=sin45cos30-sin30cos45 (which dont ask me wot that is ill have 2 think)

sin(45-30)
=sin45cos30-sin30cos45
=1/(√2)*(√2)/2 - 1/2*1/(√2)
= √3/(2√2) - 1/(2√2)
=√2(√3-1)/4

 

[Trev]

or u can put 4 eg tanx (where x is a remarkable angle) in2 the calculator.. if u get an answer which is not a rational number square it... n u will get 4 eg 3/4...

He could, but he was asking how to do it without a calculator

 

[zenger69]

learn the exact values
or use the double angle formulas for weird angles

 

[Gator]

thanks

rito thanks

i have figured it out it was queit easy when i was in a better less stressed state of mind thank you

 

[Trev]

Ah, don't worry if you don't understand it at first, I had no clue when we first started it for our first topic in preliminary. Now, it just seems second nature. Extension maths is actually quite 'easy'.

 

[Gator]

maths

oh good. well i hope your rite at moment its just racing over my head

 

[Trev]

That was exactly what happened to me start of preliminary, and they were pushing people to drop because there were 35 in the class, I thought about dropping to mathematics. In the end I came equal first. Persist!

 

[Gator]

kool

equal first well i dunno wether i will get that but i wil persist

 

[Trebla]

How about drawing the curves of sin, cos and tan? You can at least make an educated estimate on the values of each, without a calculator, (if no exact values) by interpreting their graphs, if you know them off by heart.

 

[Gator]

k

ok kool


ur in yr 11 as well arent you?