PSEB Solutions for Class 10 Maths Chapter 8 Introduction to Trigonometry Ex 8.1
PSEB Solutions for Class 10 Maths Chapter 8 Introduction to Trigonometry Ex 8.1
PSEB 10th Class Maths Solutions Chapter 8 Introduction to Trigonometry Ex 8.1
Question 1.
In ∆ABC, right angled at B, AB = 24 cm; BC = 7 cm. Determine
(i) sin A, cos A
(ii) sin C, cos C.
Solution:
(i) We are to find sin A .cos A AB = 24 cm; BC = 7 cm
By using Pythagoras Theorem,
Question 4.
Given 15 cot A = 8, find sin A and sec A.
Solution:
Let ABC be any right angled triangle where A is an acute angle with right angle at B.
Question 6.
If ∠A and ∠B are acute angles such that cos A = cos B, show that LA = LB.
Solution:
Let ABC be any triangle, where ∠A and ∠B are acute angles. To find cos A and cos B.
Question 10.
In ∆PQR, right angled at Q, PR + QR = 25 cm and PQ = 5 cm. Determine the values of sin P, cos P and tan P.
Solution:
Given: ∆PQR, right angled at Q
PR + QR = 25 cm
PQ = 5 cm
In right angled triangle PQR
By using Pythagoras Theorem,
(PR)2 = (PQ)2 + (RQ)2
or (PR)2 = (5)2 + (RQ)2
[∴ PR + QR = 25, QR = 25 – PR]
or (PR)2 = 25 + [25 – PR]2
or (PR)2 = 25 + (25)2 + (PR)2 – 2 × 25 × PR
or (PR)2 = 25 + 625 + (PR)2 – 50
or (PR)2 – (PR)2 + 50 PR = 650
or 50 PR = 650
or PR = 650/50
or PR = 13 cm
QR = 25 – PR
QR = (25 – 13) cm
or QR = 12 cm.
Question 11.
State whether the following are true or false. Justify your answer.
(i) The value of tan A is always less than 1
(ii) sec A = 12/5 for some value of angle A.
(iii) cos A is abbreviation used for cosecant of angle A.
(iv) cot A is product of cot and A.
(v) sin θ = 4/3 for some angle θ.
Solution:
(i) False
∵ tan 60° = √3 = 1.732 > 1.
(ii) True; sec A = 12/5 = 240 > 1
∵ Sec A is always greater than 1.
(iii) False.
Because cos A is used for cosine A.
(iv) False.
Because cot A is cotangent of the angle A not the product of cot and A.
(v) False; sin θ = 4/3 = 1.666 > 1
Because sin θ is always less than 1.
Follow on Facebook page – Click Here
Google News join in – Click Here
Read More Asia News – Click Here
Read More Sports News – Click Here
Read More Crypto News – Click Here