How can we draw a right angled triangle having hypotenuse of length 6.4 cm and one of the acute angle as 40 degree ?

in the right angled triangle one acute angle is 40 deg. 

therefore other angle = 90-40 = 50 deg

draw a line segment AB = 6.4 cm.

at A draw an angle of 40 deg and at B draw an angle of 50 deg.

let it intersect at C.

thus ACB is a right angled triangle , right angled at C.

and hypotenuse AB = 6.4 cm

hope this helps you.

cheers!!