Exercise 2.1 Solutions:

Question 1:
- In this question, we are given a figure with angles marked as 1, 2, 3, 4, and we need to find the value of x.
- To find the value of x, we can start by using the angle sum property of a quadrilateral, where the sum of all angles in a quadrilateral is 360 degrees.
- So, we can write an equation: 90 + 70 + x + 110 = 360
- Solving this equation, we get x = 90 degrees.

Question 2:
- In this question, we are given a figure with angles marked as a, b, c, and d, and we need to find the value of x.
- To find the value of x, we can use the property of a straight line, where the sum of angles on a straight line is 180 degrees.
- So, we can write an equation: a + b = 180
- Given that b = x, we can substitute b with x in the equation: a + x = 180
- Solving this equation, we get x = 102 degrees.

Question 3:
- In this question, we are given a figure with angles marked as x, 40, and 70, and we need to find the value of x.
- To find the value of x, we can use the property of a triangle, where the sum of angles in a triangle is 180 degrees.
- So, we can write an equation: x + 40 + 70 = 180
- Solving this equation, we get x = 70 degrees.
By following these steps and properties of angles in geometry, we can easily solve the given questions in Exercise 2.1.