The figure below is not drawn to scale. ABEF is a parallelogram and BCDE is a trapezium. BE//CD, AB//FD and BC//AD. DF is a straight line. ∠ADF=42∘\angle ADF = 42^\circ and ∠DAF=68∘\angle DAF = 68^\circ.

  1. (a)

    Find ∠BCD\angle BCD.

    Answer: ___

  2. (b)

    Find ∠ABE\angle ABE.

    Answer: ___

  3. (c)

    Find ∠BEF\angle BEF.

    Answer: ___

Work through it with AI →

It won't just hand you the answer — it asks where you're stuck.How the checker works

Worked solution

8(a)

1. Find the angle corresponding to $\angle DAF$ on the line $BE$.

Let ADAD intersect BEBE at a point PP. Since ABEFABEF is a parallelogram, AF∥BEAF \parallel BE.
Using ADAD as a transversal, the corresponding angle ∠DPE=∠DAF=68∘\angle DPE = \angle DAF = 68^\circ.

2. Find $\angle CBE$ using the parallel lines $BC$ and $AD$.

We are given that BC∥ADBC \parallel AD. Using BEBE as a transversal, the corresponding angle ∠CBE=∠DPE=68∘\angle CBE = \angle DPE = 68^\circ.

3. Calculate $\angle BCD$ using the interior angles of the trapezium.

In trapezium BCDEBCDE, we are given BE∥CDBE \parallel CD.
Interior angles between parallel lines sum to 180∘180^\circ, so:
∠BCD+∠CBE=180∘\angle BCD + \angle CBE = 180^\circ
∠BCD=180∘−68∘=112∘\angle BCD = 180^\circ - 68^\circ = 112^\circ

Answer

112∘112^\circ

8(b)

1. Find $\angle AFD$ using the sum of angles in $\triangle ADF$.

In △ADF\triangle ADF,
∠AFD=180∘−68∘−42∘=70∘\angle AFD = 180^\circ - 68^\circ - 42^\circ = 70^\circ (angle sum of triangle)

2. Find $\angle ABE$ using parallel lines.

Since AB∥FDAB \parallel FD, the interior angles ∠BAF\angle BAF and ∠AFD\angle AFD are supplementary:
∠BAF=180∘−70∘=110∘\angle BAF = 180^\circ - 70^\circ = 110^\circ

Since ABEFABEF is a parallelogram, AF∥BEAF \parallel BE. The interior angles ∠BAF\angle BAF and ∠ABE\angle ABE are supplementary:
∠ABE=180∘−110∘=70∘\angle ABE = 180^\circ - 110^\circ = 70^\circ

(Alternatively, ∠ABE=∠AFD=70∘\angle ABE = \angle AFD = 70^\circ directly since both are supplementary to ∠BAF\angle BAF)

Answer

70∘70^\circ

8(c)

1. Find $\angle AFD$ using the angle sum of $\triangle ADF$.

In △ADF\triangle ADF,
∠AFD=180∘−68∘−42∘=70∘\angle AFD = 180^\circ - 68^\circ - 42^\circ = 70^\circ

2. Find $\angle BAF$ using the parallel lines $AB$ and $FD$.

Since AB∥FDAB \parallel FD, the interior angles are supplementary:
∠BAF=180∘−∠AFD=180∘−70∘=110∘\angle BAF = 180^\circ - \angle AFD = 180^\circ - 70^\circ = 110^\circ

3. Find $\angle BEF$ using the properties of parallelogram $ABEF$.

In parallelogram ABEFABEF, opposite angles are equal:
∠BEF=∠BAF=110∘\angle BEF = \angle BAF = 110^\circ

Answer

110∘110^\circ

AI analysis — may contain mistakes.

Worked this one out on paper? Snap your steps and Gigle's AI math checker will circle the step where it went wrong.

More questions on this topic

  1. 1已知四边形ABCD,从下列条件中:(1)AB∥CD;(2)BC∥AD;(3)AB=CD;(4)BC=AD;(5)∠A=∠C;(6)∠B=∠D.任取其中两个,可以得出“四边形ABCD是平行四边形”这一结论的情况有( ) A. 4种 B. 9种…
  2. 2在四边形ABCDABCD中,已知OA→+OC→=OB→+OD→\overset\rightarrow { OA }+\overset\rightarrow { OC }=\overset\rightarrow { OB }+\overset\rightarrow { OD }…
  3. 3In the figure below, ABCD is a trapezium and AD = BC. Each of the statements is either true, false or not possible to te…
  4. 4在四边形ABCD中,对角线AC,BD交于点O,OA=OC,OB=OD,添加一个条件使四边形ABCD是矩形,那么所添加的条件可以是 ___ (写出一个即可).
  5. 5关于长方形和平行四边形的共同特点,有如下一些说法: ①对边平行;②对边相等;③四个角的和是360°;④都是轴对称图形 以上说法正确的是( ) A. ①②和③ B. ①②和④ C. ①③和④ D. ②③和④