How do you solve the triangle given a=20, c=24, B=47?

1 Answer
Dec 16, 2016

Triangle is a=20, b=17.924, c=24, A=54.7^o, B=47^o and C=78.3^o.

Explanation:

Solving a triangle means identifying length of all the three sides as well as measures of all three angles. This is generally done using Law of sines, which is a/sinA=b/sinB=c/sinC and Law of cosines, according to which b^2=a^2+c^2-2ac cosB, c^2=a^2+b^2-2abcosC and a^2=b^2+c^2-2bc cosA

Here, we are given a=20, c=24 and B=47^o.

We can use b^2=20^2+24^2-2xx20xx24xxcos47^o

= 400+576-960xx0.682=976-654.72=321.28

Hence b=sqrt321.28=17.924

Now using ^^Law of sines**

20/sinA=24/sinC=17.924/(sin47^o)=17.924/0.7314=24.5064

Hence sinA=20/24.5064=0.8161 and A=54.7^o

and sinC=24/24.5064=0.9793 and C=78.3^o

Hence, triangle is a=20, b=17.924, c=24, A=54.7^o, B=47^o and C=78.3^o.