In △ABC, AB = AC = 15 cm, BC = 18 cm. Find (i) cos ∠ABC (ii) sin ∠ACB.

Draw AD perpendicular to BC. D is mid-point of BC [∵ Perpendicular drawn to the unequal side of an isosceles triangle from the apex vertex bisects the side] ∴ BD = DC = 9 cm. In right-angled triangle ABD, ⇒ AB 2 = AD 2 + BD 2 ⇒ 15 2 = AD 2 + 9 2 ⇒ AD 2 = (15) 2 - (9) 2 ⇒ AD 2 = 225 - 81 ⇒ AD 2 = 144 ⇒ AD = = 12 cm. (i) cos ∠ABC = = . Hence, cos ∠ABC = . (ii) sin ∠ACB = = . Hence, sin ∠ACB = .

In ∆ABC, ∠A = 90°. If AB = 7 cm and BC - AC = 1 cm, find :
(i) sin C
(ii) tan B

View Answer Bookmark Now

In △PQR, ∠Q = 90°. If PQ = 40 cm and PR + QR = 50 cm, find :
(i) sin P
(ii) cos P
(iii) tan R

View Answer Bookmark Now

In the figure (1) given below, ∆ABC is isosceles with AB = AC = 5 cm and BC = 6 cm. Find
(i) sin C
(ii) tan B
(iii) tan C - cot B.

View Answer Bookmark Now

In the figure (2) given below, △ABC is right-angled at B. Given that ∠ACB = θ, side AB = 2 units and side BC = 1 unit, find the value of sin² θ + tan² θ.

View Answer Bookmark Now

Mathematics

In △ABC, AB = AC = 15 cm, BC = 18 cm. Find
(i) cos ∠ABC
(ii) sin ∠ACB.

Trigonometrical Ratios

Related Questions

In ∆ABC, ∠A = 90°. If AB = 7 cm and BC - AC = 1 cm, find :
(i) sin C
(ii) tan B

In △PQR, ∠Q = 90°. If PQ = 40 cm and PR + QR = 50 cm, find :
(i) sin P
(ii) cos P
(iii) tan R

In the figure (1) given below, ∆ABC is isosceles with AB = AC = 5 cm and BC = 6 cm. Find
(i) sin C
(ii) tan B
(iii) tan C - cot B.

In the figure (2) given below, △ABC is right-angled at B. Given that ∠ACB = θ, side AB = 2 units and side BC = 1 unit, find the value of sin² θ + tan² θ.

Mathematics

In △ABC, AB = AC = 15 cm, BC = 18 cm. Find(i) cos ∠ABC(ii) sin ∠ACB.

Trigonometrical Ratios

Related Questions

In ∆ABC, ∠A = 90°. If AB = 7 cm and BC - AC = 1 cm, find :(i) sin C(ii) tan B

In △PQR, ∠Q = 90°. If PQ = 40 cm and PR + QR = 50 cm, find :(i) sin P(ii) cos P(iii) tan R

In the figure (1) given below, ∆ABC is isosceles with AB = AC = 5 cm and BC = 6 cm. Find(i) sin C(ii) tan B(iii) tan C - cot B.

In the figure (2) given below, △ABC is right-angled at B. Given that ∠ACB = θ, side AB = 2 units and side BC = 1 unit, find the value of sin2 θ + tan2 θ.

In △ABC, AB = AC = 15 cm, BC = 18 cm. Find
(i) cos ∠ABC
(ii) sin ∠ACB.

In ∆ABC, ∠A = 90°. If AB = 7 cm and BC - AC = 1 cm, find :
(i) sin C
(ii) tan B

In △PQR, ∠Q = 90°. If PQ = 40 cm and PR + QR = 50 cm, find :
(i) sin P
(ii) cos P
(iii) tan R

In the figure (1) given below, ∆ABC is isosceles with AB = AC = 5 cm and BC = 6 cm. Find
(i) sin C
(ii) tan B
(iii) tan C - cot B.

In the figure (2) given below, △ABC is right-angled at B. Given that ∠ACB = θ, side AB = 2 units and side BC = 1 unit, find the value of sin² θ + tan² θ.