beginfig(1);
u:=0.5cm;
z0=(0,0);
x1=x2;
y1=y0;
z2=z0+9u*dir20;
draw z0--z1--z2--cycle;
draw (z1+0.5u*dir180)--(z1+0.5u*dir180+0.5u*dir90)--(z1+0.5u*dir90);
label(btex$20^\circ$etex, z0+3u*dir10);
label(btex$70^\circ$etex, z2+u*dir(-90-35));
label.ulft("9", 0.5[z0,z2]);
label.bot(btex$9\cos20^\circ\approx8.4572$etex, 0.5[z0,z1]);
label.rt(btex$9\sin20^\circ\approx3.0782$etex, 0.5[z1,z2]);
endfig;

bye