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ΔABC ∼ ΔDEF and A(ΔABC) : A Δ(DEF) = 1 : 2 If AB = 4 find DE.
Concept: Similarity of Triangles
With the help of the information given in the figure, fill in the boxes to find AB and BC .
AB = BC (Given)
∴∠ BAC = ∠ BCA =
∴ AB = BC = × AC
= × `sqrt8`
= × `2sqrt2`
= 2
Concept: Similar Triangles
From the top of a light house, an abserver looking at a boat makes an angle of depression of 600. If the height of the lighthouse is 90 m then find how far is the boat from the lighthouse. (3 = 1.73)
Concept: Property of an Angle Bisector of a Triangle
O is any point in the interior of ΔABC. Bisectors of ∠AOB, ∠BOC and ∠AOC intersect side AB, side BC, side AC in
F, D and E respectively.
Prove that
BF × AE × CD = AF × CE × BD
Concept: Similarity of Triangles
If ΔABC ~ ΔPQR and ∠A = 60°, then ∠P = ?
Concept: Similarity of Triangles
In ΔABC, ray BD bisects ∠ABC.
If A – D – C, A – E – B and seg ED || side BC, then prove that:
`("AB")/("BC") = ("AE")/("EB")`
Proof :
In ΔABC, ray BD bisects ∠ABC.
∴ `("AB")/("BC") = (......)/(......)` ......(i) (By angle bisector theorem)
In ΔABC, seg DE || side BC
∴ `("AE")/("EB") = ("AD")/("DC")` ....(ii) `square`
∴ `("AB")/square = square/("EB")` [from (i) and (ii)]
Concept: Property of an Angle Bisector of a Triangle
In ΔABC, ∠ACB = 90°. seg CD ⊥ side AB and seg CE is angle bisector of ∠ACB.
Prove that: `(AD)/(BD) = (AE^2)/(BE^2)`.
Concept: Property of an Angle Bisector of a Triangle
In the following figure, in Δ PQR, seg RS is the bisector of ∠PRQ.
PS = 11, SQ = 12, PR = 22. Find QR.
Concept: Similarity of Triangles
The ratio of the areas of two triangles with the common base is 4 : 3. Height of the larger triangle is 2 cm, then find the corresponding height of the smaller triangle.
Concept: Properties of Ratios of Areas of Two Triangles
In ∆ABC, B – D – C and BD = 7, BC = 20, then find the following ratio.
`(A(∆ABD))/(A(∆ABC))`
Concept: Properties of Ratios of Areas of Two Triangles
In the given, seg BE ⊥ seg AB and seg BA ⊥ seg AD.
if BE = 6 and AD = 9 find `(A(Δ ABE))/(A(Δ BAD))`.
Concept: Properties of Ratios of Areas of Two Triangles
In the figure, ray YM is the bisector of ∠XYZ, where seg XY ≅ seg YZ, find the relation between XM and MZ.
Concept: Property of an Angle Bisector of a Triangle
In the above figure, line l || line m and line n is a transversal. Using the given information find the value of x.
Concept: Property of Three Parallel Lines and Their Transversals
Draw seg AB = 6.8 cm and draw perpendicular bisector of it.
Concept: Property of an Angle Bisector of a Triangle
If ΔABC ~ ΔDEF, then writes the corresponding congruent angles and also write the ratio of corresponding sides.
Concept: Similarity of Triangles
Choose the correct alternative:
If ΔABC ~ ΔPQR and 4A (ΔABC) = 25 A(ΔPQR), then AB : PQ = ?
Concept: Similarity of Triangles
In the above figure, line AB || line CD || line EF, line l, and line m are its transversals. If AC = 6, CE = 9. BD = 8, then complete the following activity to find DF.
Activity :
`"AC"/"" = ""/"DF"` (Property of three parallel lines and their transversal)
∴ `6/9 = ""/"DF"`
∴ `"DF" = "___"`
Concept: Property of Three Parallel Lines and Their Transversals
In the following figure, state whether the triangles are similar. Give reason.
Concept: Similar Triangles
In the following figure, ray PT is the bisector of ∠QPR Find the value of x and perimeter of ∠QPR.
Concept: Property of an Angle Bisector of a Triangle
Sides of a triangle are 7, 24 and 25. Determine whether the triangle is a right-angled triangle or not.
Concept: Similarity of Triangles