# Pythagarous Question

#### maninthemirror

##### New member

13. The top surface of a pouch is in the shape of a rectangle LMNO with sides 9 cm and 6 cm.

(i) A zip is to be sewn along OH such that H is a point on LM and HM = 2 cm. Find the length of the zip.

(ii) A second zip is to be sewn along NK such that NK is the perpendicular from N to OH. Calculate the length of the second zip.

Hi anyone can help with (ii)???

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#### Dr.Peterson

##### Elite Member
Do you see a pair of similar triangles here? Once you have solved (i) as Khan suggested, you can compare the two triangles.

Staff member
Further Hint:

<KON = <LHO

#### Dr.Peterson

##### Elite Member
Are you asking maninthemirror if more help is needed, or are you asking if anyone else can help you solve it? In the latter case, how far did you get?

I've solved it; the hints given should be enough. Part (i) uses the Pythagorean Theorem; part (ii) most naturally uses similar triangles and the result of part (i).

#### nanaseailie

##### New member
Do you see a pair of similar triangles here? Once you have solved (i) as Khan suggested, you can compare the two triangles.
Hai dr, i just want to ask how do you determine if there are 2 similar triangles in there? I know there are two right-angled triangles, but how do you know for sure they will be similar?

#### Dr.Peterson

##### Elite Member
Do you see that angles NOK and LOH are complementary? What does that tell you about angles NOK and OHL?

#### nanaseailie

##### New member
Do you see that angles NOK and LOH are complementary? What does that tell you about angles NOK and OHL?
I see ! thanks dok