Descriptive Geometry Quiz 1

1. When constructing an isometric scale, a bse line is first established at a _____ degree angle from the X-axis.

15

25

45

None of the above

When constructing an isometric scale, a baseline is first established at a 45-degree angle from the X-axis. This angle is chosen because it allows for equal proportions and dimensions in the isometric drawing. By using a 45-degree angle, the three axes (X, Y, and Z) in the isometric drawing will have the same scale and measurements, resulting in an accurate representation of the object being drawn.

Explanation

When constructing an isometric scale, a baseline is first established at a 45-degree angle from the X-axis. This angle is chosen because it allows for equal proportions and dimensions in the isometric drawing. By using a 45-degree angle, the three axes (X, Y, and Z) in the isometric drawing will have the same scale and measurements, resulting in an accurate representation of the object being drawn.

2. The two types of orthographic projections are:

First and Third Angle

First and Second Angle

Second and Third Angle

None of the above

The correct answer is First and Third Angle. Orthographic projections are a method of representing a three-dimensional object in two dimensions. In first angle projection, the object is placed in the first quadrant of the projection plane, and the views are taken from the opposite side of the object. In third angle projection, the object is placed in the third quadrant of the projection plane, and the views are taken from the same side as the object. These two types of projections are commonly used in engineering and technical drawings.

Explanation

The correct answer is First and Third Angle. Orthographic projections are a method of representing a three-dimensional object in two dimensions. In first angle projection, the object is placed in the first quadrant of the projection plane, and the views are taken from the opposite side of the object. In third angle projection, the object is placed in the third quadrant of the projection plane, and the views are taken from the same side as the object. These two types of projections are commonly used in engineering and technical drawings.

3. A true isometric projection is constructed at a scale of 0.85 or 85% of the actual size.

True

False

An isometric projection is a method of representing a three-dimensional object on a two-dimensional surface. It maintains the proportions of the object and shows all three dimensions equally. However, the scale at which an isometric projection is constructed can vary. Therefore, it is not necessarily true that a true isometric projection is always constructed at a scale of 0.85 or 85% of the actual size. The statement is false because the scale can be different depending on the specific requirements of the projection.

Explanation

An isometric projection is a method of representing a three-dimensional object on a two-dimensional surface. It maintains the proportions of the object and shows all three dimensions equally. However, the scale at which an isometric projection is constructed can vary. Therefore, it is not necessarily true that a true isometric projection is always constructed at a scale of 0.85 or 85% of the actual size. The statement is false because the scale can be different depending on the specific requirements of the projection.

4. The three classifications of Oblique projections are:

Cabinet, General, and Horizontal

Cabinet, General, and Frontal

Cabinet, General, and Cavalier

None of the above

The correct answer is Cabinet, General, and Cavalier. These three classifications are used in the field of engineering and architecture to describe different types of oblique projections. Cabinet projection is a type of oblique projection where the depth is represented at half scale compared to the height and width. General projection is a type of oblique projection where the depth is represented at full scale. Cavalier projection is a type of oblique projection where the depth is represented at full scale and the angles between the projection lines are not distorted.

Explanation

The correct answer is Cabinet, General, and Cavalier. These three classifications are used in the field of engineering and architecture to describe different types of oblique projections. Cabinet projection is a type of oblique projection where the depth is represented at half scale compared to the height and width. General projection is a type of oblique projection where the depth is represented at full scale. Cavalier projection is a type of oblique projection where the depth is represented at full scale and the angles between the projection lines are not distorted.

5. A form of oblique projection in which the line-of-sight is drawn at a 45 degree angle from teh X-axis and the protrudting lines are drawn at half scale.

Cabinet Oblique

General Oblique

Cavalier Oblique

None of the above

Cabinet Oblique is the correct answer because it is a form of oblique projection where the line-of-sight is drawn at a 45-degree angle from the X-axis and the protruding lines are drawn at half scale. This type of oblique projection is commonly used in architectural and furniture design drawings. General Oblique and Cavalier Oblique are not correct because they do not accurately describe the specific characteristics mentioned in the question.

Explanation

Cabinet Oblique is the correct answer because it is a form of oblique projection where the line-of-sight is drawn at a 45-degree angle from the X-axis and the protruding lines are drawn at half scale. This type of oblique projection is commonly used in architectural and furniture design drawings. General Oblique and Cavalier Oblique are not correct because they do not accurately describe the specific characteristics mentioned in the question.