# Thread: Equilateral triangle and perpendicular line

1. ## equilateral triangle and perpendicularline

Originally Posted by Unknown008
Well, post what you would have done using trigonometry, I'll be happy to see how you would do it.
Hello unknown008.
byinspection the angles are
QTS 30, STR 150, TRS 15, PSR 75, PRS 45

1/sin 75= SR/sin60 SR = 0.897

0.897/sin150= ST/sin15 ST= 0.4643

bjh

2. ## equilateral triangle and perpendicular line

Hello unknown008.

PQR is an equilateral triangle PR =1 T is on QR . A line fromT to PQ is drawn perpendicular to that line meeting it @S ST =TR What length is ST?

By inspection the various angles are
QTS =30 STR=150 TRS=15 PSR=75 PRS=45 SPR= 60

Use the sine rule

1/sin75= SR/sin60 SR=0.897

0.897/sin150= ST/sin15 ST = 0.4643

bjh

3. And how am I supposed to find the exact form of ST using this?

And why did you double post?

4. Hello unknown008,
I double posted because I thought the first did not go thru. My answer was a trig solution but in looking at the question I must admit that I was wrong in thinking that trig was necessary.

bjh

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