Question: th grade math
90°
x°
30°
x =
1. **Problem Statement:** We are given a quadrilateral with two diagonals intersecting at a right angle (90°). One angle formed between the base and a diagonal is 30°, and we need to find the value of $x$ (another angle in the figure).
2. **Understanding the problem:** The diagonals intersect at 90°, and one angle adjacent to the base is 30°. We want to find $x$, which is the angle opposite or related to these given angles.
3. **Key properties:** In a parallelogram, the diagonals bisect each other. The angles around the intersection of diagonals add up to 360°, and since one angle is 90°, the adjacent angles relate accordingly.
4. **Using angle sum properties:** Since the diagonals intersect at 90°, the angles around the intersection are $90°$, $90°$, $x°$, and $x°$ (because opposite angles are equal).
5. **Calculate $x$:** The sum of angles around the intersection is
$$90° + 90° + x + x = 360°$$
6. Simplify:
$$180° + 2x = 360°$$
7. Subtract 180° from both sides:
$$\cancel{180°} + 2x = 360° - \cancel{180°}$$
$$2x = 180°$$
8. Divide both sides by 2:
$$\frac{2x}{\cancel{2}} = \frac{180°}{\cancel{2}}$$
$$x = 90°$$
9. **Final answer:**
$$\boxed{90°}$$
Thus, the value of $x$ is $90°$.