# CBSE Class 9 Mathematics Exam 2018: Important 3 Marks Questions

Feb 6, 2018 15:22 IST
CBSE Class 9 Mathematics Exam 2018

In this article you will get the most important 3 marks questions to prepare for the CBSE class 9 Mathematics annual exam 2018.

In CBSE Class 9 Mathematics Exam 2018, section - C will comprise 10 questions of 3 marks each.

All the questions given here have been picked from the most important topics of class 9 Maths. All these questions have been provided with the etailed solutions to help students make an easy and quick preparation.

By practicing these important questions, students can get an idea of the important topics and also assess their preparedness for the final exam. This will help them to fine-tune their preparation. Moreover, the solutions provided here will give students an idea to write a proper solution to each question in the exam so as to score full marks.

CBSE Class 9 Mathematics Exam 2018: Important 1 Mark Questions

Given below are some sample questions for CBSE Class 9 Mathematics: Important 3 Marks Questions:

Q. In a figure ABC is an equilateral triangle. The coordinates of vertices B and C are (3,0) and (-3,0) respectively. Find the coordinates of its vertex A.

Solution.

Given coordinates of B and C are (-4, 0) and (4, 0)
and CO = OB = 4 units
Hence O coincides with the origin.
Since ABC is an equilateral triangle, AB = BC = CA = 8 units
In right triangle AOC, AC2 = AO2 + OC2 [By Pythagoras theorem]

⟹ 82 = AO2 + 42

⟹ AO2 = 64 – 16 = 48

⟹ AO = √48 units

Hence the coordinates of A are (0, √48).

Q. Suman spins two spinners, one of which is labeled 1, 2 and 3 and the other are labeled A, B, C and D. Find the probability of:

(i) Stopping at 2 and C.

(ii) Stopping at 3 and either B or D

(iii) Stopping at any number and A

Solution.

Sample space = {A1, A2, A3, B1, B2, B3, C1, C2, C3, D1, D2, D3}

Total possible outcome = 12

Probability of stopping at 2 and C = 1/12

Probability of stopping at 3 and either B or D = 2/12 = 1/6

Probability of stopping at any number and A = 3/12 = 1/4

CBSE Class 9 Mathematics Exam 2018: Important 2 Marks Questions

Q. Construct an angle of 135o at the initial point of a given ray and justify the construction.

Solution.

Steps of construction:

1.  Draw a ray OA.

2. With its initial point O as centre and any radius, draw an arc BE, cutting OA and its produced part at C and E respectively.

3. With centre B and same radius (as in step 2), draw  an arc, cutting  the arc BE at C.

4. With C as centre and the same radius, draw an arc cutting the arc BE at D.

5. With C and D as centres, and any convenient radius (more than 1/2 CD), draw two arcs intersecting at P.

6. Join OP.

Then ∠AOP = ∠EOP = 90o

7. Draw OQ as the bisector of ∠EOP.
Then, ∠AOQ =135o

Justification :
By construction ∠AOP = 90o

Thus, ∠AOP = ∠EOP = 90o

Also, OQ is drawn as the bisector of ∠EOP

Therefore, ∠POQ =1/2∠EOP =1/2 × 90o = 45o

Thus, ∠AOQ = ∠AOP + ∠POQ = 90o + 45o = 135o

Hence justified.

To get the complete set of questions, click on the following link:

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