draw a line measuring 6
cut an angle 60 degree
extent this line and measure 5 in compass cut 5 cm and mark that point as A and join A and C
now extendent the line b cut 7 arc jon from 7th arc draw an angle on 7th arc with same compass dont chage the compass keep on 5th arc and draw an arc now measure the angle of 7th arc and with the same measurement keep on the arc which was drawn earlier on 5th arc (the arc drawn from 5th arc . the arc will touch the line from that point you have to keep ok)
after cutting that arc draw the line parallel to the next line that was joined earlier then keep on c and draw an angle measure it (same process)  YOU WILL GET THE TRIANGLE) 
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