Question 4 - Figure it out - Page 123, 124, 125 - Chapter 5 Class 7 - Parallel and Intersecting Lines (Ganita Prakash)

Transcript

Question 4 In Fig. 5.33, ∠ABC = 45° and ∠IKJ = 78°. Find angles ∠GEH, ∠HEF, ∠FED Taking two red lines as parallel lines and blue line as transversal ∠ FED (Yellow angle) and 78° are alternate exterior angles ∴ ∠ FED = 78° Now, let’s take line CH as transversal ∠ GEH + ∠ HEF + ∠ FED = 180° 45° + ∠ HEF + 78° = 180° 45° + 78° + ∠ HEF = 180° 123° + ∠ HEF = 180° ∠ HEF = 180° – 123° ∠ HEF = 57° Taking two red lines as parallel lines and yellow line as transversal ∠ GEH (Red angle) and 45° are alternate exterior angles ∴ ∠ GEH = 45° Also, Red, green and Yellow angles lie on a line By linear pair Red angle + Green angle + Yellow angle = 180°