ratios of double angles (1 Viewer)

[TheGreatest99.95]

could someone please solve and show working for:
Find exact value of:
1) sin67.5cos67.5
2) 2cos105sin105

thanks

 

[nightweaver066]

We know that

Notice that the 2x is halved among the sin and cos.

We can rearrange this equation to form:


Now with question 1.


Using exact values,



Question 2.


This is exactly the same as:


So


Using exact values,

 

[TheGreatest99.95]

thanks soo much

 

[Hermes1]

thanks soo much

hey u hav in ur sig that u are doin prelim standard english. and then in ur hsc u want to do advanced, u cant do this can u?

 

[TheGreatest99.95]

head English teacher said i can go up in year 12

 

[Hermes1]

head English teacher said i can go up in year 12

oh ok. thats nice of him, bcuz standard english would hav made getting 99+ pretty hard.