Geoffrey Cho Jian Ming's answer to JJ's Primary 5 Maths Whole Numbers Singapore question.
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As show in the diagram, AB and DC are parallel to each other. Hence, Angle ADC + Angle DAB will always add up to 180 degrees. From that logic, we can subtract the remaining values, 29 and 115 from 180 and acquire the degree of a = 36 degrees.
As for angle b, we know that it is 1/3 of angle BCF. However, we also know that triangle CFG is an isosceles triangle, meaning that the two base angles are the same. With that logic, we can take (180 - 30) / 2 to find the angle GCF, which is 75 degrees. Angle GCF and angle BCF are the same, and since angle b is 1/3 of angle BCF, we simply divide 75 by 3 and get the solve for b, which is 25 degrees.
Hope it helps!
As for angle b, we know that it is 1/3 of angle BCF. However, we also know that triangle CFG is an isosceles triangle, meaning that the two base angles are the same. With that logic, we can take (180 - 30) / 2 to find the angle GCF, which is 75 degrees. Angle GCF and angle BCF are the same, and since angle b is 1/3 of angle BCF, we simply divide 75 by 3 and get the solve for b, which is 25 degrees.
Hope it helps!
Date Posted:
1 year ago
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