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# Visualization and Sketching

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## 3.27 Angles in Oblique Projection

When an angle that is specified in degrees lies in a receding plane, convert the angle into linear measurements to draw the angle in an oblique drawing. Figure 3.65a shows a drawing with an angle of 30° specified.

To draw the angle in the oblique drawing, you will need to know distance X. The distance from point A to point B is given as 32 mm. This can be measured directly in the cavalier drawing (Figure 3.65b). Find distance X by drawing the right triangle ABC (Figure 3.65c) using the dimensions given, which is quick and easy using CAD.

You can also use a mathematical solution to find the length of the side: The length of the opposite side equals the tangent of the angle times the length of the adjacent side. In this case, the length of the opposite side, X, is about 18.5 mm. Draw the angle in the cavalier drawing using the found distance.

Remember that all receding dimensions must be reduced to match the scale of the receding axis. In the cabinet drawing in Figure 3.65c, the distance BC must be half the side BC of the right triangle in Figure 3.65c.