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Triangle. Ratio of the area of triangles. Theorem 1. Example In the figure, BC// DE, AC= 3 cm and CE= 4 cm. Find. Class work In the figure, PSQ, QXR and RYP are straight lines. If the area of is , find the area of the parallelogram SXRY.
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Ratio of the area of triangles Theorem 1
Example In the figure, BC// DE, AC= 3 cm and CE= 4 cm. Find
Class work In the figure, PSQ, QXR and RYP are straight lines. If the area of is , find the area of the parallelogram SXRY.
81 36 Area of parallelogram = 225 – 81 - 36 = 108 Area of parallelogram is
Triangle C height A B base
Triangle base height
Triangle base height
Area of Triangle C height A B base
For triangles with commonheight, Theorem 2
Eg.3) Given that BC : DC = 5: 1 Find and have common height,
Eg.3) Given that BC : DC = 5: 1 Find and have common height, = 4
Eg.4) Given that AD = 3 cm and CD = 1 cm. Find and have common height,
Class work 5.) In the figure, find the area of : area of .
Class work 5.) In the figure, find the area of : area of .
Class work 5.) In the figure, find the area of : area of . = 1
6.) In the figure, given that QX:XR = 5:6 and PY:YR =5:3 calculate the area of (a) (b)
6.) In the figure, given that QX:XR = 5:6 and PY:YR =5:3 5x 6x
6.) In the figure, given that QX:XR = 5:6 and PY:YR =5:3 5x 6x
6.) In the figure, given that QX:XR = 5:6 and PY:YR =5:3 5y 3y 5x 6x
6.) In the figure, given that QX:XR = 5:6 and PY:YR =5:3 5y 3y 5x 6x
7) In the figure, PQRS is a rectangle. M is a midpoint of QR. PR and MS intersects at N. Find the area of : area of PQMN.
In the figure, PQRS is a rectangle. M is a midpoint of QR. PR and MS intersects at N. Find the area of : area of PQMN.
In the figure, PQRS is a rectangle. M is a midpoint of QR. PR and MS intersects at N. Find the area of : area of PQMN.
Find the area of : area of PQMN. 4A A = 4
Find the area of : area of PQMN. 4A 2y 2A y A Considering They have the common height.
Find the area of : area of PQMN. 4A 2y 2A y A Hence, = 2A : 5A = 2 : 5
8.) In the figure, PX:XQ = 1: 2, PY:YR = 3:2. Area of : Area of = ?
In the figure, PX:XQ = 1: 2, PY:YR = 3:2. Area of : Area of = ? and have the common height
In the figure, PX:XQ = 1: 2, PY:YR = 3:2. Area of : Area of = ? and have the common height
In the figure, PX:XQ = 1: 2, PY:YR = 3:2. Area of : Area of = ? and have the common height = 2A : 5A = 2 : 5
9.) In the figure, PQRS is a rectangle. RSX is a straight line and PX// QS. If the area of PQRS is 24 and Y is a point on QR such that QY :YR = 3:1, find the area of .
10.) In the figure, if , Find
10.) In the figure, if , A 3A
10.) In the figure, if , A x 3A 3x
10.) In the figure, if , A x 3A 3x 9A
10.) In the figure, if , A x 3A 3A 3x 9A
10.) In the figure, if , A x 3A 3A 3x 9A
Ratio of the area of similar triangles Theorem 1
For triangles with commonheight, Theorem 2