Ask Singapore Homework?

Upload a photo of a Singapore homework and someone will email you the solution for free.



Question

secondary 4 | A Maths
3 Answers Below

Anyone can contribute an answer, even non-tutors.

Answer This Question
Sonia
Sonia

secondary 4 chevron_right A Maths chevron_right Singapore

Morning!!!! can someone please help me with this qns ? Thx youuuu

Date Posted: 1 month ago
Views: 12

See 3 Answers

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Bern Ong @ 88Tuition
Bern Ong @ 88tuition's answer
97 answers (A Helpful Person)
1st
Keep Trying, you can do it;)
Eric Nicholas K
Eric Nicholas K
1 month ago
One correction. Cos theta/2 cannot stay +-. This is because theta/2 is guaranteed to be between 90 and 135 and so its cosine will have a negative value.
Bern Ong @ 88Tuition
Bern Ong @ 88Tuition
1 month ago
Good Catch, Thank you Eric. ;)
done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
DAI BIN
Dai Bin's answer
78 answers (Tutor Details)
done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Eric Nicholas K
Eric Nicholas K's answer
3828 answers (Tutor Details)
Good morning Sonia! I hope you have made good progress in your revision! Here is my variant of the workings.

I used a basic angle’s triangle instead so that I do not have to worry about where to place the negative signs in the triangle. Instead, I place a negative sign afterwards in front of the sine, cosine or tangent based on my knowledge of A-S-T-C.

We use the double angle formula in both cases and we have to determine the direct quadrant in which the new angles lie in.

Let me know if you need more explanation and I will do my best to explain them again.
Sonia
Sonia
1 month ago
Thank you so much Eric! I’ve made some improvements and i’m so happy! i hope i can perform well in my upcoming Os :(