Half of 90 is 45

Three 15 degree angles make 45 degrees

another one makes 60

15+15+15+15=45

another 15 equals 60

15+15+15+15+15=60

another equals 75

15+15+15+15+15+15=75

90-75=15

so a 75 degree angle is one 15 degree angle short of a right angle

Let’s first construct 60 degrees. We know that, in a right triangle, the side twice as short as the hypotenuse is opposite to the 30-degree angle. Therefore, the other acute angle in the triangle is 60 degrees. Now, bisect the 60-degree angle, and bisect each of its halves. One quarter of 60 degrees is 15 degrees. Having thus constructed 60 degrees and 15 degrees, add the two angles to get 75.

Draw a line.

Spread your compass a little bit.

Place the point on the line.

Draw an arc that crosses the line and goes up from where you have the point.

Now, place the point where that arc crossed the line.

Draw another arc that passes through the line and the first arc.

Connect the points where the arcs cross the line to the point where the arcs cross. You formed an equililateral triangle where all the inside angles are 60 degrees.

Now, at teh point where one of the arcs crossed the line, make a perpindicular line from there. That’s a 90 degree line.

75 degrees is halfway between 90 and 60, right?

Bisect the angle formed by the vertical line and the side of the triangle.

the bisect to the original line forms 75 degrees.

RE:
how do i construct a 75 degree angle? explain?
k i have to construct a 75 degree angle, i knw i need to make a 60 degree anlge and a 15 degree angle but idk how to make that with a compass and ruler. and i cant use a protract. please explain to me how i can construct this. thank you.