PSLE ABCD and CFHE are identical parallelograms. GCB and EDC are identical right-angled triangles.
- Find ∠j.
- Find ∠k.
- Select the words that describe BGF in the statement:
BGF (is/is not) a straight line because the sum of angles BGC and CGF (is/is not) 180° Give your answers in this format. (Eg is, is not)
(a)
∠j
= 180° - 77°
= 103° (Interior angles)
(b)
∠ECF
= ∠BCD
= 103° (Parallelogram)
∠BCG
= 180° - 90° - 28°
= 62° (Angles sum of triangle)
∠k
= 360° - 103° - 103° - 28° - 62°
= 64° (Angles at a point)
(c)
∠CGF
= 180° - 27° - 64°
= 89°
Since ∠CGF is not 90°, it does not add up to 180° with ∠BGC to form a straight line. So, BGF
is not a straight line because the sum of angles BGC and CGF
is not 180°.
Answer(s): (a) 103°; (b) 62°; (c) is not, is not