AL Maths Edexcel Textbook Question Year 2

Ok so this question is from Pure Year 2 Maths Exercise 5B and its Q3. They say that DC=2 square root 2 but I don't get how? They did 2 divided by sin pi/3 which gave 4 root 3 all over 3. What formula did they use in this step to get the length of AC as this?

Reply 1

mqb2766

Original post by pigeonwarrior

Can you post a pic of the question?

sin(pi/3) = sqrt(3)/2
so
2/sin(pi/3) = 2/(sqrt(3)/2) = 4/sqrt(3) = 4sqrt(3)/3

(edited 5 months ago)

Reply 2

pigeonwarrior

Original post by mqb2766

Can you post a pic of the question?

sin(pi/3) = sqrt(3)/2
so
2/sin(pi/3) = 2/(sqrt(3)/2) = 4/sqrt(3) = 4sqrt(3)/3

I will try!

Reply 3

pigeonwarrior

Original post by mqb2766

Can you post a pic of the question?

sin(pi/3) = sqrt(3)/2
so
2/sin(pi/3) = 2/(sqrt(3)/2) = 4/sqrt(3) = 4sqrt(3)/3

I can't 😭 but I'll type the question.

The diagram shows a right-angled triangle ACD on another right-angled triangle ABC with AD=2 root 6 all over 3 and BC=2. Show that DC=k root 2 where k is a constant to be determined.

Reply 4

pigeonwarrior

Original post by pigeonwarrior

I will try!

[Solved] The diagram shows a right-angled triangle | SolutionInn

This shows the diagram in the question

Reply 5

mqb2766

Original post by pigeonwarrior

[Solved] The diagram shows a right-angled triangle | SolutionInn

This shows the diagram in the question

Ok, so you should have CA from #1 (edited part) and then its just pythagoras? Are you ok now?

(edited 5 months ago)

Reply 6

pigeonwarrior

Original post by mqb2766

Ok, so you should have CA from #1 (edited part) and then its just pythagoras? Are you ok now?

Hii thank you for responding! How did they get AC as 4 root 3 all over 3? As in what formula are they using?

Reply 7

mqb2766

Original post by pigeonwarrior

Hii thank you for responding! How did they get AC as 4 root 3 all over 3? As in what formula are they using?

The numbers are in #1 and you may be overthinking the formula
sin() = opp/hyp
and as AC is the hyp
AC = opp/sin()

The question is just a combination of straightforward trig and pythagoras.

(edited 5 months ago)

Reply 8

pigeonwarrior

Original post by mqb2766

The numbers are in #1 and you may be overthinking the formula
sin() = opp/hyp
and as AC is the hyp
AC = opp/sin()

Its just a combination of straightforward trig and pythagoras.

OH MY GOD I AM EMBARRASSED! But in my self defence I have covid soo...😅
Thank you so so much I was trying to use the sine rule and other formulas but SOH CAH TOA is much easier! Once again, thank you for all your help!