An equilateral triangle fits into its outline three times in a full 360° turn. Image caption, An isosceles triangle has two sides that are equal in length. Isosceles means equal legs. The ‘legs ...

Look high in the southeast sky, near Orion's belt, after sunset. Sirius, the brightest of the three stars, will appear first, followed by Procyon and Betelgeuse. The triangle is visible until the ...