Q 3. Construct an isosceles right-angled triangle ABC, where and AC = 6 cm.
1. Draw CA = 6 cm
2. Draw a perpendicular CX to CA at C
3. From C and with length = 6 cm cut an arc on CX. The arc meet CX at B
4. Join BA
Triangle ABC is the required triangle
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Q 2. Construct a right-angled triangle whose hypotenuse is 6 cm long and one of the legs is 4 cm long.
a right-angled triangle whose hypotenuse is 6 cm long and one of the legs is 4 cm long:
1. Draw QR = 4 cm
2. Draw a perpendicular QX to QR at Q
3. From R and with length = 6 cm cut an arc on QX. The arc meet QX at P
4. Join PR
Triangle PQR is the required triangle
View Full Answer(1)Q 1. Construct the right angled , where , QR = 8cm and PR = 10 cm.
the right-angled , where , QR = 8cm and PR = 10 cm:
1. Draw QR = 8 cm
2. Draw a perpendicular QX to QR at Q
3. From R and with length = 10 cm cut an arc on QX. The arc meet QX at P
4. Join PR
PQR is the required triangle
View Full Answer(1)Q 11. ABC and ADC are two right triangles with common hypotenuse AC. Prove that $\angle C A D=\angle C B D$..
Given: ABC and ADC are two right triangles with common hypotenuse AC.
To prove : $\angle C A D=\angle C B D$
Proof :
Triangle ABC and ADC are on a common base BC and $\angle \mathrm{BAC}=\angle \mathrm{BDC}$.
Thus, points A, B, C, and D lie in the same circle.
(If a line segment joining two points subtends equal angles at two other points lying on the same side of the line containing the line segment, four points lie on the circle.)
$\angle C A D=\angle C B D$ (Angles in the same segment are equal)
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Q : 9 Two circles intersect at two points B and C. Through B, two line segments ABD and PBQ are drawn to intersect the circles at A, D and P, Q respectively (see Fig. ). Prove that .
................1(vertically opposite angles)
..................2(Angles in the same segment are equal)
.................3(angles in the same segment are equal)
From 1,2,3 ,we get
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Q 5. Prove that the circle drawn with any side of a rhombus as diameter, passes through the point of intersection of its diagonals.
Given : ABCD is rhombus.
To prove : the circle drawn with AB as diameter, passes through the point O.
Proof :
ABCD is a rhombus.
Thus, $\angle A O B=90^{\circ} \quad$ (diagonals of a rhombus bisect each other at $90^{\circ}$ )
So, a circle drawn AB as diameter will pass through point O .
Thus, the circle is drawn with any side of a rhombus as the diameter passes through the point of intersection of its diagonals.
View Full Answer(1)Q 12. Prove that a cyclic parallelogram is a rectangle.
Given: ABCD is a cyclic quadrilateral.
To prove: ABCD is a rectangle.
Proof :
In cyclic quadrilateral ABCD.
$\angle A+\angle C=180^{\circ}$------1(sum of either pair of opposite angles of a cyclic quadrilateral)
$\angle A=\angle C$------2(opposite angles of a parallelogram are equal )
From 1 and 2,
$\angle A+\angle A=180^{\circ}$
$\Rightarrow 2 \angle A=180^{\circ}$
$\Rightarrow \angle A=90^{\circ}$
We know that a parallelogram with one angle right angle is a rectangle.
Hence, $A B C D$ is a rectangle.
Q 10. If circles are drawn taking two sides of a triangle as diameters, prove that the point of intersection of these circles lies on the third side.
Given: circles are drawn taking two sides of a triangle as diameters.
Construction: Join AD.
Proof: $A B$ is the diameter of the circle and $\angle A D B$ is formed in a semi-circle.
$\angle A D B=90^{\circ}$-------1 (angle in a semi-circle)
Similarly,
$A C$ is the diameter of the circle and $\angle A D C$ is formed in a semi-circle.
$\angle A D C=90^{\circ}$------2(angle in a semi-circle)
From 1 and 2, we have
$\angle \mathrm{ADB}+\angle \mathrm{ADC}=90^{\circ}+90^{\circ}=180^{\circ}$
$\angle A D B$ and $\angle A D C$ are forming a linear pair.
Hence, point D lies on this side.
View Full Answer(1)Q: 8 If the non-parallel sides of a trapezium are equal, prove that it is cyclic.
Given: $ABCD$ is a trapezium.
Construction: Draw $AD || BE$.
Proof: In quadrilateral $ABED$,
$AB || DE$ (Given)
$AD || BE$ (By construction)
Thus, $ABED$ is a parallelogram.
$AD = BE$ (Opposite sides of the parallelogram )
$AD = BC$ (Given)
So, $BE = BC$
In $\triangle EBC$,
$BE = BC$ (Proved above)
Thus, $\angle C=\angle 2$-----1(angles opposite to equal sides)
$\angle A=\angle 1$-------2(Opposite angles of the parallelogram)
From 1 and 2 , we get
$\angle 1+\angle 2=180^{\circ}$
$\Rightarrow \angle A+\angle C=180^{\circ}$
Thus, $ABED$ is a cyclic quadrilateral.
Q: 7 If diagonals of a cyclic quadrilateral are diameters of the circle through the vertices of the quadrilateral, prove that it is a rectangle.
AC is the diameter of the circle.
Thus, $\angle A D C=90^{\circ}$ and $\angle A B C=90^{\circ}$--------1(Angle in a semi-circle is right angle)
Similarly, BD is the diameter of the circle.
Thus, $\angle B A D=90^{\circ}$ and $\angle B C D=90^{\circ}$--------2(Angle in a semi-circle is right angle)
From 1 and 2, we get
$\angle B C D=\angle A D C=\angle A B C=\angle B A D=90^{\circ}$
Hence, $A B C D$ is a rectangle.
Study 40% syllabus and score up to 100% marks in JEE
Construct an isosceles right-angled triangle ABC, where m∠ACB = 90° and AC = 6 cm.
Construct a right-angled triangle whose hypotenuse is 6 cm long and one of the legs is 4 cm long.
Construct the right angled ∆PQR, where m∠Q = 90°, QR = 8cm and PR = 10 cm.
ABC and ADC are two right triangles with common hypotenuse AC. Prove that ∠ CAD = ∠ CBD.
Prove that a cyclic parallelogram is a rectangle.
If the non-parallel sides of a trapezium are equal, prove that it is cyclic.