angle of inclination; tilt angle
Technical term used in geometry, engineering, and physics to describe the angle between a line or plane and a reference plane, typically the horizontal.
The angle of inclination of this slope is about 30 degrees.
If the tilt angle is too steep, vehicles cannot climb it.
角度 is a general term for any angle, whereas 傾斜角 is specifically the angle of inclination or tilt.
Compound of 傾斜 (keisha, 'inclination, slope') and 角 (kaku, 'angle'). The reading is the standard on'yomi for each kanji.