Question

Suppose an isosceles triangle ABC has A = pi/6 and b = c = 5. What is the length of a^2?

Answer 1

use the cosine rule :
a^2 = b^2 + c^2 - 2bc*cosA

Answer 2

i never learned that

Answer 3

these are my options

Answer 4

u have learned, now :)
just put the value of them ...
a^2 = b^2 + c^2 - 2bc*cosA
a^2 = 5^2 + 5^2 - 2(5)(5)cos(pi/6)
a^2 = 25+25 - 50*1/2*sqrt(3)
a^2 = 50 - 25 sqrt(3)
a^2 = 25 (2 - sqrt(3))
a^2 = 5^2 (2 - sqrt(3))

Answer 5

thankyou so much... clear example!!!:)

Answer 6

very welcome :)