Q2 of 45 Page 68

Find the value of x in the diagram below.


We know by proposition 1,


∠DAB + ∠BAC = 180°


130° + ∠BAC = 180°


∠BAC = 180° - 130°


∠BAC = 50°


And again We know by proposition 1,


∠BCE + ∠BCA = 180°


90° + ∠BCA = 180°


∠BCA = 180° - 90°


∠BCA = 90°


In triangle ABC,


∠ACB + ∠BAC + ∠CBA = 180°


90° + 50° + ∠CBA = 180°


∠CBA = 180° - 140°


∠CBA = 40°


∠BFG = x = ∠CBA = 40° (alteranate angles)


More from this chapter

All 45 →
5

Suppose two adjacent angles are supplementary. Show that if one of them is an obtuse angle, then the other angle must be acute.

 1

Find all the angles in the following figure.

 3

Show that if a straight line is perpendicular to one of the two or more parallel lines, then it is also perpendicular to the remaining lines.

 4

Let and be two parallel lines and be a transversal. Show that the angle bisectors of a pair of two internal angles on the same side of the transversal are perpendicular to each other.