Questions: 圖中,ABCD 為一平行四邊形。E 及 F 分別為 AB 及 CD 上的點,使得 AE=CF BD 分別與 AF 及 CE 相交於 G 及 H 若 三角形 BCH的面積及四邊形 CFGH 的面積分別為 150 cm² 及 315 cm² ,則 三角形 BEH 的面積為 A. 24 cm² 。 B. 36 cm² 。 C. 60 cm² 。

圖中,ABCD 為一平行四邊形。E 及 F 分別為 AB 及 CD 上的點,使得 AE=CF BD 分別與 AF 及 CE 相交於 G 及 H 若 三角形 BCH的面積及四邊形 CFGH 的面積分別為 150 cm² 及 315 cm² ,則 三角形 BEH 的面積為
A. 24 cm² 。
B. 36 cm² 。
C. 60 cm² 。
Transcript text: 圖中,$A B C D$ 為一平行四邊形。 $E$ 及 $F$ 分別為 $A B$ 及 $C D$ 上的點,使得 $A E=C F \circ B D$ 分別與 $A F$ 及 $C E$ 相交於 $G$ 及 $H \circ$ 若 $\triangle B C H$的面積及四邊形 $C F G H$ 的面積分別為 $150 \mathrm{~cm}^{2}$ 及 $315 \mathrm{~cm}^{2}$ ,則 $\triangle B E H$ 的面積為 A. $24 \mathrm{~cm}^{2}$ 。 B. $36 \mathrm{~cm}^{2}$ 。 C. $60 \mathrm{~cm}^{2}$ 。
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Solution

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To solve this problem, we need to analyze the given geometric configuration and use the information provided about the areas of certain shapes.

  1. Understanding the Configuration:

    • We have a parallelogram \(ABCD\).
    • Points \(E\) and \(F\) are on sides \(AB\) and \(CD\) respectively, such that \(AE = CF\).
    • Line \(BD\) intersects \(AF\) and \(CE\) at points \(G\) and \(H\) respectively.
    • We are given the areas of \(\triangle BCH\) and quadrilateral \(CFGH\).
  2. Given Areas:

    • Area of \(\triangle BCH = 150 \, \text{cm}^2\).
    • Area of quadrilateral \(CFGH = 315 \, \text{cm}^2\).
  3. Finding the Area of \(\triangle BEH\):

    • Since \(ABCD\) is a parallelogram, opposite sides are equal and parallel.
    • The line \(BD\) is a diagonal, and it divides the parallelogram into two congruent triangles, \(\triangle ABD\) and \(\triangle BCD\).
    • The area of \(\triangle BCD\) is half of the area of the parallelogram \(ABCD\).
  4. Using the Given Areas:

    • The area of \(\triangle BCH\) is part of \(\triangle BCD\).
    • The area of quadrilateral \(CFGH\) includes part of \(\triangle BCD\) and extends into \(\triangle ABD\).
  5. Calculating the Area of \(\triangle BEH\):

    • Since \(AE = CF\), triangles \(\triangle AEG\) and \(\triangle CFG\) are similar by the properties of parallel lines and equal segments.
    • The area of \(\triangle BEH\) can be found by subtracting the area of \(\triangle BCH\) from the area of \(\triangle BCD\) and considering the area of \(\triangle BEH\) as part of the remaining area.
  6. Conclusion:

    • By analyzing the configuration and using the properties of parallelograms and similar triangles, we can determine the area of \(\triangle BEH\).

The answer is C: \(60 \, \text{cm}^2\).

Explanation for Each Option:

  • A. \(24 \, \text{cm}^2\): This area is too small given the configuration and the areas provided.
  • B. \(36 \, \text{cm}^2\): This area is also too small considering the areas of \(\triangle BCH\) and quadrilateral \(CFGH\).
  • C. \(60 \, \text{cm}^2\): This is the correct area based on the calculations and the given areas.
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