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° - 78°
= 102° (Interior angles)
(b)
∠ECF
= ∠BCD
= 102° (Parallelogram)
∠BCG
= 180° - 90° - 27°
= 63° (Angles sum of triangle)
∠k
= 360° - 102° - 102° - 27° - 63°
= 66° (Angles at a point)
(c)
∠CGF
= 180° - 24° - 66°
= 90°
Since ∠CGF is 90°, it adds up to 180° with ∠BGC to form a straight line. So, BGF
is a straight line because the sum of angles BGC and CGF
is 180°.
Answer(s): (a) 102°; (b) 63°; (c) is, is