किसी वस्तु का ऊर्ध्वाधर तल (Vertical plane) पर प्रक्षेपित दृश्य क्या कहलाता है?

In an isometric drawing projection, the angle between any two adjacent isometric axes is:

In technical engineering drawing, when the plan view (top view) is drawn directly below the front view, which type of orthographic projection system is being utilized?