Trigonometric equations help

Hi, I’m trying to do my maths homework, and I’m on the last question, but I’m really stuck. Can someone help me with how to do this. I don’t just want answers to copy though, an explanation would be greatly appreciated. Thanks

6C48D6F3-F47D-4908-AA89-EC7D871322B6.jpg.jpeg

6C48D6F3-F47D-4908-AA89-EC7D871322B6.jpg.jpeg

Reply 1

Notnek

21

Original post by Himynameisdaisy

Hi, I’m trying to do my maths homework, and I’m on the last question, but I’m really stuck. Can someone help me with how to do this. I don’t just want answers to copy though, an explanation would be greatly appreciated. Thanks

6C48D6F3-F47D-4908-AA89-EC7D871322B6.jpg.jpeg

Can you see how you can manipulate the equation to involve

\tan \theta

?

Original post by Himynameisdaisy

Hi, I’m trying to do my maths homework, and I’m on the last question, but I’m really stuck. Can someone help me with how to do this. I don’t just want answers to copy though, an explanation would be greatly appreciated. Thanks

Divide both sides by

\cos \theta

. (IMPORTANT: Think about why we are allowing to divide through by it!)

Then the equation becomes

\sqrt{3}\tan \theta = 1

.

Also, do you mean just part (iii) or the entire Q7 ?

Reply 3

MarkFromWales

10

7 (i) Replace cos²θ with 1 - sin²θ.
Re-arrange to form a standard quadratic equation in sinθ.
Solve the quadratic equation to find sinθ.
Solve again to find any values of θ in the domain given.

Reply 4

MarkFromWales

10

Did you mean that question 7 is the last question on your homework and you are stuck on question 7,
or did you mean that you are stuck on the last part of question 7, that's (iii) ! ?

Reply 5

stress-eating

14

for ii) 2sinxcosx can be simplified into the identity sin2x. Then equal sin2x to sinx, so you get 0. I mean you can get 0 just from looking at it but I'm guessing the marks are for recognising the trigonometric identity.