Question

Class 9 maths circles ​

Answer 1

Answer:

SUM OF MEASURE OF ANGLES OF A TRIANGLE IS 180°

Therefore IN TRIANGLE DBC

LDBC+ LBDC+LDCB= 180

69+LBDC+31= 180

LBDC +31 = 180- 69

LBDC +31= 111

LBDC = 111-31

LBDC= 80°

TO CHECK THE ANSWER WE CAN ADD ALL THE ANGLES IF THE ANSWER IS EQUAL TO 180° THEN THE ANSWER IS CORRECT

HERE, 69+31+80 gives us 180 therefore our answer is correct

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