In the figure, a piece of paper PQRS in the shape of a parallelogram is folded along 2 dotted lines, TS and UR as shown in Figure 1. In Figure 2, ∠PST=32∘\angle PST = 32^\circ and ∠QRS=14∘\angle QRS = 14^\circ.

  1. (a)

    Find ∠UQR\angle UQR in Figure 2.

  2. (b)

    Find ∠QRU\angle QRU in Figure 2.

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

10(a)

1. Relate the folded angle $\angle UQR$ to the original angle of the parallelogram.

When the paper is folded, the angle ∠UQR\angle UQR in Figure 2 corresponds directly to the original interior angle ∠PQR\angle PQR of the parallelogram PQRS before folding because the shape around Q is preserved under folding.

Since PQRS is a parallelogram, the opposite interior angles are equal:
∠PQR=∠PSR\angle PQR = \angle PSR

2. Calculate the original interior angle $\angle PSR$ to find $\angle UQR$.

The fold line TSTS is perpendicular to the parallel horizontal sides PQPQ and SRSR of the parallelogram. Therefore, the angle between the vertical line TSTS and the base SRSR is 90∘90^\circ (i.e., ∠TSR=90∘\angle TSR = 90^\circ).

The full angle at SS before folding, ∠PSR\angle PSR, is the sum of the angle of the folded part and the right angle:
∠PSR=∠PST+∠TSR=32∘+90∘=122∘\angle PSR = \angle PST + \angle TSR = 32^\circ + 90^\circ = 122^\circ

Thus,
∠UQR=∠PSR=122∘\angle UQR = \angle PSR = 122^\circ

Answer

122∘122^\circ

10(b)

1. Find the interior angles of the original parallelogram PQRS.

In the original parallelogram PQRSPQRS, we are given in the folding diagram that after folding along the vertical line TSTS, the remaining angle is 32∘32^\circ.
Since TS⊥PQTS \perp PQ, in the unfolded state, the angle at SS of the right-angled triangle is 90∘−58∘=32∘90^\circ - 58^\circ = 32^\circ.
Therefore, the original angle ∠PSR\angle PSR of the parallelogram is:
∠PSR=90∘+32∘=122∘\angle PSR = 90^\circ + 32^\circ = 122^\circ
Since adjacent angles in a parallelogram sum to 180∘180^\circ, the original angle ∠QRS\angle QRS is:
∠QRSoriginal=180∘−122∘=58∘\angle QRS_{\text{original}} = 180^\circ - 122^\circ = 58^\circ

2. Use the symmetry of the fold UR to find the angle $\angle QRU$.

When the corner containing QQ is folded along the line URUR, the original angle ∠QRSoriginal\angle QRS_{\text{original}} is divided into three parts: the folded angle ∠QRU\angle QRU, the overlapping region underneath (which is also equal to ∠QRU\angle QRU due to folding symmetry), and the remaining unfolded angle ∠QRSremaining=14∘\angle QRS_{\text{remaining}} = 14^\circ shown in Figure 2.

Thus, the folding relation gives:
2×∠QRU+14∘=∠QRSoriginal2 \times \angle QRU + 14^\circ = \angle QRS_{\text{original}}
2×∠QRU+14∘=58∘2 \times \angle QRU + 14^\circ = 58^\circ
2×∠QRU=58∘−14∘=44∘2 \times \angle QRU = 58^\circ - 14^\circ = 44^\circ
∠QRU=22∘\angle QRU = 22^\circ

Answer

52∘52^\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